diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
deleted file mode 100644
index 30aa626c..00000000
--- a/.idea/codeStyles/Project.xml
+++ /dev/null
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\ No newline at end of file
diff --git a/.idea/extended_image.iml b/.idea/extended_image.iml
deleted file mode 100644
index c9d208a4..00000000
--- a/.idea/extended_image.iml
+++ /dev/null
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\ No newline at end of file
diff --git a/.idea/libraries/Dart_Packages.xml b/.idea/libraries/Dart_Packages.xml
deleted file mode 100644
index e187acc4..00000000
--- a/.idea/libraries/Dart_Packages.xml
+++ /dev/null
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-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/package_config-1.1.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/path-1.6.2/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/path_provider-1.1.2/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/path_provider-1.3.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/pedantic-1.8.0+1/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/petitparser-2.4.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/platform-2.2.1/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/pub_semver-1.4.2/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/pull_to_refresh_notification-0.3.2/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/quiver-2.0.3/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/source_span-1.5.5/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/stack_trace-1.9.3/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/stream_channel-2.0.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/string_scanner-1.0.4/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/term_glyph-1.1.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/test_api-0.2.5/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/typed_data-1.1.6/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/url_launcher-5.1.2/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/vector_math-2.0.8/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/watcher-0.9.7+12/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/xml-3.5.0/lib" />
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/yaml-2.1.16/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/pkg/sky_engine/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/packages/flutter/lib" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/packages/flutter_test/lib" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
\ No newline at end of file
diff --git a/.idea/libraries/Dart_SDK.xml b/.idea/libraries/Dart_SDK.xml
deleted file mode 100644
index 5b0bb5b3..00000000
--- a/.idea/libraries/Dart_SDK.xml
+++ /dev/null
@@ -1,28 +0,0 @@
-<component name="libraryTable">
-  <library name="Dart SDK">
-    <CLASSES>
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/async" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/cli" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/collection" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/convert" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/core" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/developer" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/ffi" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/html" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/indexed_db" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/io" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/isolate" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/js" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/js_util" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/math" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/mirrors" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/svg" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/typed_data" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/web_audio" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/web_gl" />
-      <root url="file://$PROJECT_DIR$/../../../flutter_source/master/bin/cache/dart-sdk/lib/web_sql" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
\ No newline at end of file
diff --git a/.idea/libraries/Flutter_Plugins.xml b/.idea/libraries/Flutter_Plugins.xml
deleted file mode 100644
index 166c9cb7..00000000
--- a/.idea/libraries/Flutter_Plugins.xml
+++ /dev/null
@@ -1,9 +0,0 @@
-<component name="libraryTable">
-  <library name="Flutter Plugins" type="FlutterPluginsLibraryType">
-    <CLASSES>
-      <root url="file://$USER_HOME$/AppData/Roaming/Pub/Cache/hosted/pub.flutter-io.cn/path_provider-1.1.2" />
-    </CLASSES>
-    <JAVADOC />
-    <SOURCES />
-  </library>
-</component>
\ No newline at end of file
diff --git a/.idea/markdown-navigator.xml b/.idea/markdown-navigator.xml
deleted file mode 100644
index d51909ce..00000000
--- a/.idea/markdown-navigator.xml
+++ /dev/null
@@ -1,82 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="MarkdownProjectSettings" wasCopied="true">
-    <PreviewSettings splitEditorLayout="SPLIT" splitEditorPreview="PREVIEW" useGrayscaleRendering="false" zoomFactor="1.5" maxImageWidth="0" showGitHubPageIfSynced="false" allowBrowsingInPreview="false" synchronizePreviewPosition="true" highlightPreviewType="NONE" highlightFadeOut="5" highlightOnTyping="true" synchronizeSourcePosition="true" verticallyAlignSourceAndPreviewSyncPosition="true" showSearchHighlightsInPreview="false" showSelectionInPreview="true" openRemoteLinks="true" replaceUnicodeEmoji="false" lastLayoutSetsDefault="false">
-      <PanelProvider>
-        <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.panel" providerName="Default - Swing" />
-      </PanelProvider>
-    </PreviewSettings>
-    <ParserSettings gitHubSyntaxChange="false" emojiShortcuts="1" emojiImages="0">
-      <PegdownExtensions>
-        <option name="ABBREVIATIONS" value="false" />
-        <option name="ANCHORLINKS" value="true" />
-        <option name="ASIDE" value="false" />
-        <option name="ATXHEADERSPACE" value="true" />
-        <option name="AUTOLINKS" value="true" />
-        <option name="DEFINITIONS" value="false" />
-        <option name="DEFINITION_BREAK_DOUBLE_BLANK_LINE" value="false" />
-        <option name="FENCED_CODE_BLOCKS" value="true" />
-        <option name="FOOTNOTES" value="false" />
-        <option name="HARDWRAPS" value="false" />
-        <option name="HTML_DEEP_PARSER" value="false" />
-        <option name="INSERTED" value="false" />
-        <option name="QUOTES" value="false" />
-        <option name="RELAXEDHRULES" value="true" />
-        <option name="SMARTS" value="false" />
-        <option name="STRIKETHROUGH" value="true" />
-        <option name="SUBSCRIPT" value="false" />
-        <option name="SUPERSCRIPT" value="false" />
-        <option name="SUPPRESS_HTML_BLOCKS" value="false" />
-        <option name="SUPPRESS_INLINE_HTML" value="false" />
-        <option name="TABLES" value="true" />
-        <option name="TASKLISTITEMS" value="true" />
-        <option name="TOC" value="false" />
-        <option name="WIKILINKS" value="true" />
-      </PegdownExtensions>
-      <ParserOptions>
-        <option name="ADMONITION_EXT" value="false" />
-        <option name="ATTRIBUTES_EXT" value="false" />
-        <option name="COMMONMARK_LISTS" value="true" />
-        <option name="DUMMY" value="false" />
-        <option name="EMOJI_SHORTCUTS" value="true" />
-        <option name="ENUMERATED_REFERENCES_EXT" value="false" />
-        <option name="FLEXMARK_FRONT_MATTER" value="false" />
-        <option name="GFM_LOOSE_BLANK_LINE_AFTER_ITEM_PARA" value="false" />
-        <option name="GFM_TABLE_RENDERING" value="true" />
-        <option name="GITBOOK_URL_ENCODING" value="false" />
-        <option name="GITHUB_LISTS" value="false" />
-        <option name="GITHUB_WIKI_LINKS" value="true" />
-        <option name="GITLAB_EXT" value="false" />
-        <option name="GITLAB_MATH_EXT" value="false" />
-        <option name="GITLAB_MERMAID_EXT" value="false" />
-        <option name="HEADER_ID_NO_DUPED_DASHES" value="false" />
-        <option name="JEKYLL_FRONT_MATTER" value="false" />
-        <option name="MACROS_EXT" value="false" />
-        <option name="NO_TEXT_ATTRIBUTES" value="false" />
-        <option name="PARSE_HTML_ANCHOR_ID" value="false" />
-        <option name="SIM_TOC_BLANK_LINE_SPACER" value="true" />
-      </ParserOptions>
-    </ParserSettings>
-    <HtmlSettings headerTopEnabled="false" headerBottomEnabled="false" bodyTopEnabled="false" bodyBottomEnabled="false" embedUrlContent="false" addPageHeader="true" embedImages="false" embedHttpImages="false" imageUriSerials="false" addDocTypeHtml="true">
-      <GeneratorProvider>
-        <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.generator" providerName="Default Swing HTML Generator" />
-      </GeneratorProvider>
-      <headerTop />
-      <headerBottom />
-      <bodyTop />
-      <bodyBottom />
-    </HtmlSettings>
-    <CssSettings previewScheme="UI_SCHEME" cssUri="" isCssUriEnabled="false" isCssUriSerial="false" isCssTextEnabled="false" isDynamicPageWidth="true">
-      <StylesheetProvider>
-        <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.css" providerName="Default Swing Stylesheet" />
-      </StylesheetProvider>
-      <ScriptProviders />
-      <cssText />
-      <cssUriHistory />
-    </CssSettings>
-    <HtmlExportSettings updateOnSave="false" parentDir="" targetDir="" cssDir="" scriptDir="" plainHtml="false" imageDir="" copyLinkedImages="false" imageUniquifyType="0" targetExt="" useTargetExt="false" noCssNoScripts="false" linkToExportedHtml="true" exportOnSettingsChange="true" regenerateOnProjectOpen="false" linkFormatType="HTTP_ABSOLUTE" />
-    <LinkMapSettings>
-      <textMaps />
-    </LinkMapSettings>
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/markdown-navigator/profiles_settings.xml b/.idea/markdown-navigator/profiles_settings.xml
deleted file mode 100644
index 57927c5a..00000000
--- a/.idea/markdown-navigator/profiles_settings.xml
+++ /dev/null
@@ -1,3 +0,0 @@
-<component name="MarkdownNavigator.ProfileManager">
-  <settings default="" pdf-export="" />
-</component>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
deleted file mode 100644
index 32684726..00000000
--- a/.idea/misc.xml
+++ /dev/null
@@ -1,28 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="NullableNotNullManager">
-    <option name="myDefaultNullable" value="android.support.annotation.Nullable" />
-    <option name="myDefaultNotNull" value="android.support.annotation.NonNull" />
-    <option name="myNullables">
-      <value>
-        <list size="5">
-          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.Nullable" />
-          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nullable" />
-          <item index="2" class="java.lang.String" itemvalue="javax.annotation.CheckForNull" />
-          <item index="3" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
-          <item index="4" class="java.lang.String" itemvalue="android.support.annotation.Nullable" />
-        </list>
-      </value>
-    </option>
-    <option name="myNotNulls">
-      <value>
-        <list size="4">
-          <item index="0" class="java.lang.String" itemvalue="org.jetbrains.annotations.NotNull" />
-          <item index="1" class="java.lang.String" itemvalue="javax.annotation.Nonnull" />
-          <item index="2" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.NonNull" />
-          <item index="3" class="java.lang.String" itemvalue="android.support.annotation.NonNull" />
-        </list>
-      </value>
-    </option>
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
deleted file mode 100644
index 7d1209e8..00000000
--- a/.idea/modules.xml
+++ /dev/null
@@ -1,8 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ProjectModuleManager">
-    <modules>
-      <module fileurl="file://$PROJECT_DIR$/.idea/extended_image.iml" filepath="$PROJECT_DIR$/.idea/extended_image.iml" />
-    </modules>
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
deleted file mode 100644
index 35eb1ddf..00000000
--- a/.idea/vcs.xml
+++ /dev/null
@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="VcsDirectoryMappings">
-    <mapping directory="" vcs="Git" />
-  </component>
-</project>
\ No newline at end of file
diff --git a/.idea/workspace.xml b/.idea/workspace.xml
deleted file mode 100644
index 2ad3b295..00000000
--- a/.idea/workspace.xml
+++ /dev/null
@@ -1,340 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project version="4">
-  <component name="ChangeListManager">
-    <list default="true" id="a4c2fe2a-3599-4f0f-a4fb-15a0db06eabb" name="Default" comment="">
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/codeStyles/Project.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/libraries/Dart_SDK.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/markdown-navigator.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/markdown-navigator/profiles_settings.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/misc.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/modules.xml" />
-      <change beforePath="" afterPath="$PROJECT_DIR$/.idea/vcs.xml" />
-      <change beforePath="$PROJECT_DIR$/.idea/extended_image.iml" afterPath="$PROJECT_DIR$/.idea/extended_image.iml" />
-      <change beforePath="$PROJECT_DIR$/.idea/libraries/Dart_Packages.xml" afterPath="$PROJECT_DIR$/.idea/libraries/Dart_Packages.xml" />
-    </list>
-    <option name="EXCLUDED_CONVERTED_TO_IGNORED" value="true" />
-    <option name="TRACKING_ENABLED" value="true" />
-    <option name="SHOW_DIALOG" value="false" />
-    <option name="HIGHLIGHT_CONFLICTS" value="true" />
-    <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
-    <option name="LAST_RESOLUTION" value="IGNORE" />
-  </component>
-  <component name="FileEditorManager">
-    <leaf>
-      <file leaf-file-name="pubspec.yaml" pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/example/pubspec.yaml">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="-1053">
-              <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-              <folding />
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file leaf-file-name="main.dart" pinned="false" current-in-tab="true">
-        <entry file="file://$PROJECT_DIR$/example/lib/main.dart">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="-1053">
-              <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-              <folding>
-                <element signature="e#0#17#0" expanded="true" />
-              </folding>
-            </state>
-          </provider>
-        </entry>
-      </file>
-      <file leaf-file-name="pubspec.yaml" pinned="false" current-in-tab="false">
-        <entry file="file://$PROJECT_DIR$/pubspec.yaml">
-          <provider selected="true" editor-type-id="text-editor">
-            <state relative-caret-position="0">
-              <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-              <folding />
-            </state>
-          </provider>
-        </entry>
-      </file>
-    </leaf>
-  </component>
-  <component name="Git.Settings">
-    <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
-  </component>
-  <component name="GradleLocalSettings">
-    <option name="externalProjectsViewState">
-      <projects_view />
-    </option>
-  </component>
-  <component name="ProjectFrameBounds" extendedState="6">
-    <option name="x" value="-10" />
-    <option name="y" value="7" />
-    <option name="width" value="1904" />
-    <option name="height" value="1023" />
-  </component>
-  <component name="ProjectView">
-    <navigator currentView="ProjectPane" proportions="" version="1">
-      <flattenPackages />
-      <showMembers />
-      <showModules />
-      <showLibraryContents />
-      <hideEmptyPackages />
-      <abbreviatePackageNames />
-      <autoscrollToSource />
-      <autoscrollFromSource />
-      <sortByType />
-      <manualOrder />
-      <foldersAlwaysOnTop value="true" />
-    </navigator>
-    <panes>
-      <pane id="AndroidView" />
-      <pane id="PackagesPane" />
-      <pane id="Scope" />
-      <pane id="ProjectPane">
-        <subPane>
-          <expand>
-            <path>
-              <item name="extended_image" type="b2602c69:ProjectViewProjectNode" />
-              <item name="extended_image" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="extended_image" type="b2602c69:ProjectViewProjectNode" />
-              <item name="extended_image" type="462c0819:PsiDirectoryNode" />
-              <item name="example" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="extended_image" type="b2602c69:ProjectViewProjectNode" />
-              <item name="extended_image" type="462c0819:PsiDirectoryNode" />
-              <item name="example" type="462c0819:PsiDirectoryNode" />
-              <item name="lib" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="extended_image" type="b2602c69:ProjectViewProjectNode" />
-              <item name="extended_image" type="462c0819:PsiDirectoryNode" />
-              <item name="lib" type="462c0819:PsiDirectoryNode" />
-            </path>
-            <path>
-              <item name="extended_image" type="b2602c69:ProjectViewProjectNode" />
-              <item name="extended_image" type="462c0819:PsiDirectoryNode" />
-              <item name="lib" type="462c0819:PsiDirectoryNode" />
-              <item name="src" type="462c0819:PsiDirectoryNode" />
-            </path>
-          </expand>
-          <select />
-        </subPane>
-      </pane>
-      <pane id="Scratches" />
-    </panes>
-  </component>
-  <component name="PropertiesComponent">
-    <property name="android.sdk.path" value="$USER_HOME$/AppData/Local/Android/Sdk" />
-    <property name="settings.editor.selected.configurable" value="flutter.settings" />
-    <property name="last_opened_file_path" value="$PROJECT_DIR$" />
-    <property name="show.migrate.to.gradle.popup" value="false" />
-    <property name="dart.analysis.tool.window.force.activate" value="false" />
-    <property name="io.flutter.reload.alreadyRun" value="true" />
-  </component>
-  <component name="RunDashboard">
-    <option name="ruleStates">
-      <list>
-        <RuleState>
-          <option name="name" value="ConfigurationTypeDashboardGroupingRule" />
-        </RuleState>
-        <RuleState>
-          <option name="name" value="StatusDashboardGroupingRule" />
-        </RuleState>
-      </list>
-    </option>
-  </component>
-  <component name="RunManager">
-    <configuration default="true" type="AndroidJUnit" factoryName="Android JUnit">
-      <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
-      <module name="" />
-      <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-      <option name="ALTERNATIVE_JRE_PATH" />
-      <option name="PACKAGE_NAME" />
-      <option name="MAIN_CLASS_NAME" />
-      <option name="METHOD_NAME" />
-      <option name="TEST_OBJECT" value="class" />
-      <option name="VM_PARAMETERS" value="-ea" />
-      <option name="PARAMETERS" />
-      <option name="WORKING_DIRECTORY" value="$MODULE_DIR$" />
-      <option name="ENV_VARIABLES" />
-      <option name="PASS_PARENT_ENVS" value="true" />
-      <option name="TEST_SEARCH_SCOPE">
-        <value defaultName="singleModule" />
-      </option>
-      <envs />
-      <patterns />
-    </configuration>
-    <configuration default="true" type="Application" factoryName="Application">
-      <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
-      <option name="MAIN_CLASS_NAME" />
-      <option name="VM_PARAMETERS" />
-      <option name="PROGRAM_PARAMETERS" />
-      <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$" />
-      <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-      <option name="ALTERNATIVE_JRE_PATH" />
-      <option name="ENABLE_SWING_INSPECTOR" value="false" />
-      <option name="ENV_VARIABLES" />
-      <option name="PASS_PARENT_ENVS" value="true" />
-      <module name="" />
-      <envs />
-    </configuration>
-    <configuration name="main.dart" type="FlutterRunConfigurationType" factoryName="Flutter">
-      <option name="filePath" value="$PROJECT_DIR$/example/lib/main.dart" />
-    </configuration>
-    <configuration default="true" type="Remote" factoryName="Remote">
-      <option name="USE_SOCKET_TRANSPORT" value="true" />
-      <option name="SERVER_MODE" value="false" />
-      <option name="SHMEM_ADDRESS" value="javadebug" />
-      <option name="HOST" value="localhost" />
-      <option name="PORT" value="5005" />
-    </configuration>
-    <configuration default="true" type="TestNG" factoryName="TestNG">
-      <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
-      <module name="" />
-      <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-      <option name="ALTERNATIVE_JRE_PATH" />
-      <option name="SUITE_NAME" />
-      <option name="PACKAGE_NAME" />
-      <option name="MAIN_CLASS_NAME" />
-      <option name="METHOD_NAME" />
-      <option name="GROUP_NAME" />
-      <option name="TEST_OBJECT" value="CLASS" />
-      <option name="VM_PARAMETERS" value="-ea" />
-      <option name="PARAMETERS" />
-      <option name="WORKING_DIRECTORY" value="%MODULE_WORKING_DIR%" />
-      <option name="OUTPUT_DIRECTORY" />
-      <option name="ANNOTATION_TYPE" />
-      <option name="ENV_VARIABLES" />
-      <option name="PASS_PARENT_ENVS" value="true" />
-      <option name="TEST_SEARCH_SCOPE">
-        <value defaultName="singleModule" />
-      </option>
-      <option name="USE_DEFAULT_REPORTERS" value="false" />
-      <option name="PROPERTIES_FILE" />
-      <envs />
-      <properties />
-      <listeners />
-    </configuration>
-    <configuration name="&lt;template&gt;" type="Applet" default="true" selected="false">
-      <option name="MAIN_CLASS_NAME" />
-      <option name="HTML_FILE_NAME" />
-      <option name="HTML_USED" value="false" />
-      <option name="WIDTH" value="400" />
-      <option name="HEIGHT" value="300" />
-      <option name="POLICY_FILE" value="$APPLICATION_HOME_DIR$/bin/appletviewer.policy" />
-      <option name="VM_PARAMETERS" />
-    </configuration>
-    <configuration name="&lt;template&gt;" type="JUnit" default="true" selected="false">
-      <option name="MAIN_CLASS_NAME" />
-      <option name="VM_PARAMETERS" value="-ea" />
-      <option name="PARAMETERS" />
-      <option name="WORKING_DIRECTORY" value="%MODULE_WORKING_DIR%" />
-    </configuration>
-    <configuration name="&lt;template&gt;" type="#org.jetbrains.idea.devkit.run.PluginConfigurationType" default="true" selected="false">
-      <option name="VM_PARAMETERS" value="-Xmx512m -Xms256m -XX:MaxPermSize=250m -ea" />
-    </configuration>
-  </component>
-  <component name="ShelveChangesManager" show_recycled="false">
-    <option name="remove_strategy" value="false" />
-  </component>
-  <component name="SvnConfiguration">
-    <configuration />
-  </component>
-  <component name="TaskManager">
-    <task active="true" id="Default" summary="Default task">
-      <changelist id="a4c2fe2a-3599-4f0f-a4fb-15a0db06eabb" name="Default" comment="" />
-      <created>1567844999849</created>
-      <option name="number" value="Default" />
-      <option name="presentableId" value="Default" />
-      <updated>1567844999849</updated>
-    </task>
-    <task id="LOCAL-00001" summary="update image editor">
-      <created>1567846111172</created>
-      <option name="number" value="00001" />
-      <option name="presentableId" value="LOCAL-00001" />
-      <option name="project" value="LOCAL" />
-      <updated>1567846111172</updated>
-    </task>
-    <option name="localTasksCounter" value="2" />
-    <servers />
-  </component>
-  <component name="ToolWindowManager">
-    <frame x="-11" y="-11" width="1942" height="1042" extended-state="6" />
-    <layout>
-      <window_info id="TODO" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="6" side_tool="false" content_ui="tabs" />
-      <window_info id="Messages" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.3289941" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Palette&#9;" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Image Layers" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Capture Analysis" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
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-      <window_info id="Version Control" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
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-      <window_info id="Designer" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Project" active="true" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="true" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="0" side_tool="false" content_ui="combo" />
-      <window_info id="Structure" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="1" side_tool="false" content_ui="tabs" />
-      <window_info id="Theme Preview" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
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-      <window_info id="Flutter Inspector" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="-1" side_tool="false" content_ui="tabs" />
-      <window_info id="Cvs" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="4" side_tool="false" content_ui="tabs" />
-      <window_info id="Message" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="0" side_tool="false" content_ui="tabs" />
-      <window_info id="Commander" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.4" sideWeight="0.5" order="0" side_tool="false" content_ui="tabs" />
-      <window_info id="Inspection" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.4" sideWeight="0.5" order="5" side_tool="false" content_ui="tabs" />
-      <window_info id="Captures" active="false" anchor="left" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="2" side_tool="false" content_ui="tabs" />
-      <window_info id="Hierarchy" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="2" side_tool="false" content_ui="combo" />
-      <window_info id="Find" active="false" anchor="bottom" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.33" sideWeight="0.5" order="1" side_tool="false" content_ui="tabs" />
-      <window_info id="Ant Build" active="false" anchor="right" auto_hide="false" internal_type="DOCKED" type="DOCKED" visible="false" show_stripe_button="true" weight="0.25" sideWeight="0.5" order="1" side_tool="false" content_ui="tabs" />
-    </layout>
-  </component>
-  <component name="VcsContentAnnotationSettings">
-    <option name="myLimit" value="2678400000" />
-  </component>
-  <component name="VcsManagerConfiguration">
-    <MESSAGE value="update image editor" />
-    <option name="LAST_COMMIT_MESSAGE" value="update image editor" />
-  </component>
-  <component name="XDebuggerManager">
-    <breakpoint-manager />
-    <watches-manager />
-  </component>
-  <component name="editorHistoryManager">
-    <entry file="file://$PROJECT_DIR$/lib/src/edit/extended_image_crop_layer.dart">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="0">
-          <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-          <folding />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/pubspec.yaml">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="0">
-          <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-          <folding />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/example/pubspec.yaml">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="-1053">
-          <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-          <folding />
-        </state>
-      </provider>
-    </entry>
-    <entry file="file://$PROJECT_DIR$/example/lib/main.dart">
-      <provider selected="true" editor-type-id="text-editor">
-        <state relative-caret-position="-1053">
-          <caret line="0" column="0" lean-forward="false" selection-start-line="0" selection-start-column="0" selection-end-line="0" selection-end-column="0" />
-          <folding>
-            <element signature="e#0#17#0" expanded="true" />
-          </folding>
-        </state>
-      </provider>
-    </entry>
-  </component>
-</project>
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63a8bd4e..6c272c74 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## [0.6.1]
+
+* Issues:
+  Fix issue about drag slowly in ImageEditor
+
 ## [0.6.0]
 
 * Issues:
diff --git a/example/android/app/build.gradle b/example/android/app/build.gradle
index 9b2b9052..78268e52 100644
--- a/example/android/app/build.gradle
+++ b/example/android/app/build.gradle
@@ -25,8 +25,7 @@ apply plugin: 'com.android.application'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 27
-
+    compileSdkVersion 28
     lintOptions {
         disable 'InvalidPackage'
     }
@@ -35,7 +34,7 @@ android {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "com.zmtzawqlp.example"
         minSdkVersion 16
-        targetSdkVersion 27
+        targetSdkVersion 28
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
diff --git a/example/android/gradle.properties b/example/android/gradle.properties
index 8bd86f68..7be3d8b4 100644
--- a/example/android/gradle.properties
+++ b/example/android/gradle.properties
@@ -1 +1,2 @@
 org.gradle.jvmargs=-Xmx1536M
+android.enableR8=true
diff --git a/example/lib/example_route_helper.dart b/example/lib/example_route_helper.dart
index adb20f81..754d4ae2 100644
--- a/example/lib/example_route_helper.dart
+++ b/example/lib/example_route_helper.dart
@@ -1,7 +1,7 @@
 // GENERATED CODE - DO NOT MODIFY BY HAND
 // **************************************************************************
 // auto generated by https://github.com/fluttercandies/ff_annotation_route
-// ************************************************************************** 
+// **************************************************************************
 
 import 'package:flutter/widgets.dart';
 
@@ -13,7 +13,7 @@ class FFNavigatorObserver extends NavigatorObserver {
 
   @override
   void didPop(Route route, Route previousRoute) {
-    super.didPop(route, previousRoute);    
+    super.didPop(route, previousRoute);
     _showStatusBarChange(previousRoute, route);
     _routeChange(previousRoute);
   }
@@ -27,14 +27,14 @@ class FFNavigatorObserver extends NavigatorObserver {
 
   @override
   void didRemove(Route route, Route previousRoute) {
-     super.didRemove(route, previousRoute);
+    super.didRemove(route, previousRoute);
     _showStatusBarChange(previousRoute, route);
-    _routeChange(previousRoute);  
+    _routeChange(previousRoute);
   }
 
   @override
   void didReplace({Route newRoute, Route oldRoute}) {
-     super.didReplace(newRoute: newRoute, oldRoute: oldRoute);
+    super.didReplace(newRoute: newRoute, oldRoute: oldRoute);
     _showStatusBarChange(newRoute, oldRoute);
     _routeChange(newRoute);
   }
@@ -117,7 +117,6 @@ Widget _defaultTransitionsBuilder(
   return child;
 }
 
-
 class FFRouteSettings extends RouteSettings {
   final String routeName;
   final bool showStatusBar;
diff --git a/lib/src/editor/extended_image_editor.dart b/lib/src/editor/extended_image_editor.dart
index 3dfe613e..abf8bcc9 100644
--- a/lib/src/editor/extended_image_editor.dart
+++ b/lib/src/editor/extended_image_editor.dart
@@ -194,6 +194,7 @@ class ExtendedImageEditorState extends State<ExtendedImageEditor> {
     var delta = (details.focalPoint - _startingOffset);
     var scaleDelta = totalScale / _editActionDetails.preTotalScale;
     _startingOffset = details.focalPoint;
+
     //no more zoom
     if (details.scale != 1.0 &&
         (
@@ -210,7 +211,10 @@ class ExtendedImageEditorState extends State<ExtendedImageEditor> {
     if (mounted && (scaleDelta != 1.0 || delta != Offset.zero)) {
       setState(() {
         _editActionDetails.totalScale = totalScale;
-        _editActionDetails.delta = delta;
+
+        ///if we have shift offset, we should clear delta.
+        ///we should += delta in case miss delta
+        _editActionDetails.delta += delta;
       });
     }
   }
diff --git a/lib/src/editor/extended_image_editor_utils.dart b/lib/src/editor/extended_image_editor_utils.dart
index a6e89e17..2af693df 100644
--- a/lib/src/editor/extended_image_editor_utils.dart
+++ b/lib/src/editor/extended_image_editor_utils.dart
@@ -197,12 +197,15 @@ class EditActionDetails {
             _screenDestinationRect.width * scaleDelta,
             _screenDestinationRect.height * scaleDelta);
         preTotalScale = totalScale;
+        delta = Offset.zero;
       }
 
       /// move
       else {
-        if (_screenDestinationRect != screenCropRect)
+        if (_screenDestinationRect != screenCropRect) {
           _screenDestinationRect = _screenDestinationRect.shift(delta);
+        }
+        //we have shift offset, we should clear delta.
         delta = Offset.zero;
       }
 
diff --git a/pubspec.yaml b/pubspec.yaml
index d2d8bac8..a128b2ae 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: extended_image
 description: Official extension image, support placeholder(loading)/ failed state, cache network, zoom/pan, photo view, slide out page, editor(crop,rotate,flip), painting etc.
-version: 0.6.0
+version: 0.6.1
 author: zmtzawqlp <zmtzawqlp@live.com>
 homepage: https://github.com/fluttercandies/extended_image