Add overflow option to drawText() API

Originally requested here: geongeorge/Canvas-Txt#83 And fix proposed here: geongeorge/Canvas-Txt#94 By default, text overflows. Set to `false` to clip the text to the specified box.
stefcameron · Mar 13, 2024 · e2d7ef2 · e2d7ef2
1 parent a56c1c6
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## UNRELEASED
+
+### Added
+
+- New `overflow?: boolean` config parameter for `drawText()` API: True (default) to allow overflow; false to clip text to box.
+
 ## v1.0.0
 
 - First official release 🎉
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -41,17 +41,16 @@ Run `npm test`, the Docs app, and the Node demo and manually verify your changes
 
 ## Pull requests
 
-Always include a new bullet point in the [CHANGELOG](./CHANGELOG.md) under the __UNRELEASED__ heading at the very top.
+Always include a new bullet point (CD, Change Description) in the [CHANGELOG](./CHANGELOG.md) under the __UNRELEASED__ heading at the very top, linking to the issue being addressed when applicable, typically ending your CD with `([#123](https://github.com/stefcameron/text-to-canvas/issues/123))`
 
-Include your change description in one of the following subsections under "UNRELEASED":
+Include your CD in one of the following subsections under "UNRELEASED":
 
-> If an "UNRELEASED" heading doesn't exist, please add one!
+> If an `## UNRELEASED` heading doesn't exist, please add one!
 
--   "Breaking": If your change alters an existing API/type in a way that is not backward-compatible, or makes use of a Web API that doesn't yet have wide browser support.
+-   `### Breaking`: If your change alters an existing API/type in a way that is not backward-compatible, or makes use of a Web API that doesn't yet have wide browser support.
     -   __AVOID__ this type of change as best as possible.
--   "Added": If your change adds a new feature without breaking anything pre-existing.
--   "Changed": If your change alters existing behavior without breaking anything pre-existing, including bug fixes.
+-   `### Added`: If your change adds a new feature without breaking anything pre-existing.
+-   `### Changed`: If your change alters existing behavior without breaking anything pre-existing, including bug fixes.
     -   If you're fixing a bug, try to start your change description with, "Fixed ..."
--   Always link to the issue being addressed when applicable, typically ending your change description with `([#123](https://github.com/stefcameron/text-to-canvas/issues/123))`
 
 And please fill-out the pull request template when prompted!
diff --git a/src/docs/AppCanvas.vue b/src/docs/AppCanvas.vue
@@ -19,6 +19,7 @@ const initialConfig = {
   vAlign: 'middle',
   justify: false,
   debug: false,
+  overflow: true,
 };
 
 const config = reactive(cloneDeep(initialConfig));
@@ -52,6 +53,7 @@ function renderText() {
     vAlign: config.vAlign,
     justify: config.justify,
     debug: config.debug,
+    overflow: config.overflow,
     // currently not configurable in demo UI
     fontFamily: 'Times New Roman, serif',
     fontSize: 24,
@@ -163,9 +165,10 @@ onMounted(() => {
             size="small"
           />
         </div>
+
         <br />
-        <el-row>
-          <el-col :span="12">
+        <el-row :gutter="12">
+          <el-col :span="8">
             <el-form-item label="Horizontal Align">
               <el-select v-model="config.align" placeholder="Align">
                 <el-option label="Center" value="center" />
@@ -174,7 +177,7 @@ onMounted(() => {
               </el-select>
             </el-form-item>
           </el-col>
-          <el-col :span="12">
+          <el-col :span="8">
             <el-form-item label="Vertical Align">
               <el-select v-model="config.vAlign" placeholder="vAlign">
                 <el-option label="Middle" value="middle" />
@@ -183,12 +186,15 @@ onMounted(() => {
               </el-select>
             </el-form-item>
           </el-col>
+          <el-col :span="8">
+            <el-checkbox v-model="config.justify" label="Justify" />
+          </el-col>
         </el-row>
         <br />
 
-        <el-row>
+        <el-row :gutter="12">
           <el-col :span="12">
-            <el-checkbox v-model="config.justify" label="Justify Text" />
+            <el-checkbox v-model="config.overflow" label="Overflow" />
           </el-col>
           <el-col :span="12">
             <el-checkbox v-model="config.debug" label="Debug mode" />

diff --git a/src/lib/index.ts b/src/lib/index.ts
@@ -22,6 +22,13 @@ const drawText = (
     fontWeight: config.fontWeight,
   });
 
+  const {
+    width: boxWidth,
+    height: boxHeight,
+    x: boxX = 0,
+    y: boxY = 0,
+  } = config;
+
   const {
     lines: richLines,
     height: totalHeight,
@@ -33,8 +40,8 @@ const drawText = (
     inferWhitespace: Array.isArray(text)
       ? config.inferWhitespace === undefined || config.inferWhitespace
       : undefined, // ignore since `text` is a string; we assume it already has all the whitespace it needs
-    x: config.x || 0,
-    y: config.y || 0,
+    x: boxX,
+    y: boxY,
     width: config.width,
     height: config.height,
     align: config.align,
@@ -49,6 +56,12 @@ const drawText = (
   ctx.font = getTextStyle(baseFormat);
   ctx.fillStyle = baseFormat.fontColor || DEFAULT_FONT_COLOR;
 
+  if (config.overflow === false) {
+    ctx.beginPath();
+    ctx.rect(boxX, boxY, boxWidth, boxHeight);
+    ctx.clip(); // part of saved context state
+  }
+
   richLines.forEach((line) => {
     line.forEach((pw) => {
       if (!pw.isWhitespace) {
@@ -71,40 +84,39 @@ const drawText = (
   });
 
   if (config.debug) {
-    const { width, height, x = 0, y = 0 } = config;
-    const xEnd = x + width;
-    const yEnd = y + height;
+    const xEnd = boxX + boxWidth;
+    const yEnd = boxY + boxHeight;
 
     let textAnchor: number;
     if (config.align === 'right') {
       textAnchor = xEnd;
     } else if (config.align === 'left') {
-      textAnchor = x;
+      textAnchor = boxX;
     } else {
-      textAnchor = x + width / 2;
+      textAnchor = boxX + boxWidth / 2;
     }
 
-    let debugY = y;
+    let debugY = boxY;
     if (config.vAlign === 'bottom') {
       debugY = yEnd;
     } else if (config.vAlign === 'middle') {
-      debugY = y + height / 2;
+      debugY = boxY + boxHeight / 2;
     }
 
     const debugColor = '#0C8CE9';
 
     // Text box
     ctx.lineWidth = 1;
     ctx.strokeStyle = debugColor;
-    ctx.strokeRect(x, y, width, height);
+    ctx.strokeRect(boxX, boxY, boxWidth, boxHeight);
 
     ctx.lineWidth = 1;
 
     if (!config.align || config.align === 'center') {
       // Horizontal Center
       ctx.strokeStyle = debugColor;
       ctx.beginPath();
-      ctx.moveTo(textAnchor, y);
+      ctx.moveTo(textAnchor, boxY);
       ctx.lineTo(textAnchor, yEnd);
       ctx.stroke();
     }
@@ -113,7 +125,7 @@ const drawText = (
       // Vertical Center
       ctx.strokeStyle = debugColor;
       ctx.beginPath();
-      ctx.moveTo(x, debugY);
+      ctx.moveTo(boxX, debugY);
       ctx.lineTo(xEnd, debugY);
       ctx.stroke();
     }

diff --git a/src/lib/model.ts b/src/lib/model.ts
@@ -105,9 +105,6 @@ export interface DrawTextConfig extends TextFormat {
   justify?: boolean;
 
   /**
-   * __NOTE:__ Applies only if `text`, given to `drawText()`, is a `Word[]`. Ignored if it's
-   *  a `string`.
-   *
    * True indicates `text` is a `Word` array that contains _mostly_ visible words and
    *  whitespace should be inferred _unless a word is whitespace (e.g. a new line or tab)_, based
    *  on the context's general text formatting style (i.e. every space will use the font style set
@@ -116,11 +113,22 @@ export interface DrawTextConfig extends TextFormat {
    *  as Words with `text="\n"`).
    *
    * False indicates that `words` contains its own whitespace and it shouldn't be inferred.
+   *
+   * ❗️ Applies only if `text`, given to `drawText()`, is a `Word[]`. Ignored if it's
+   *  a `string`.
    */
   inferWhitespace?: boolean;
 
   /** True if debug lines should be rendered behind the text. */
   debug?: boolean;
+
+  /**
+   * True (default) if the text should overflow the box's boundaries when it's either too
+   *  tall or too wide to fit.
+   *
+   * False if the text should be clipped to the box's boundaries.
+   */
+  overflow?: boolean;
 }
 
 export interface BaseSplitProps {