如何使用画布使用背景颜色绘制文本

Question

我有一些代码,我在位图(画布)上绘制我的文字

canvas.drawTextOnPath(Text, textPath[count], gipa, -10, text);

请告诉我,可以在路径(textPath)中使用背景颜色绘制此文本吗？

它只是绘制文本的全部功能

 public void drawText(float x,float y ,String Text,Canvas canvas,Paint paint1 ,int count )
        {
            float xren =text.measureText(Text.trim());

            canvas.drawTextOnPath(Text, textPath[count], gipa, -10, text);

        }

使用此功能我在画布上绘制文字.那么如何修改这个函数来用背景绘制这个文本？

Answer 1

这里很可能需要两个步骤.您将首先沿路径绘制一条线,背景颜色,然后按照指示绘制文本.使用绘制对象设置线条的粗细.此外,改变油漆的风格可以有助于产生效果.尝试FILL,STROKE或FILL_AND_STROKE为不同的效果.

mpaint.setStyle(Paint.Style.STROKE);
mpaint.setStrokeWidth(strokeWidth);

添加样本以绘制红色的路径(矩形):

         Paint mPaint = new Paint();
         mPaint.setColor(Color.RED);
         Path mPath = new Path();
         RectF mRectF = new RectF(20, 20, 240, 240);
         mPath.addRect(mRectF, Path.Direction.CCW);
         mPaint.setStrokeWidth(20);
         mPaint.setStyle(Paint.Style.STROKE);
         canvas.drawPath(mPath, mPaint);

然后沿同一路径绘制文本(蓝色):

        mPaint.setColor(Color.BLUE);
         mPaint.setStrokeWidth(0);
         mPaint.setStyle(Paint.Style.FILL);
         mPaint.setTextSize(20);
         canvas.drawTextOnPath("Draw the text, with origin at (x,y), using the specified paint, along the specified path.", mPath, 0, 5, mPaint);

Answer 2

如果你想这样做，那么实现下面的代码片段：

     /**
     * PUT THIS METHOD FOR IMPLEMENT WATER-MARK IN COMMON FILE
     */
    public static Bitmap waterMark(Bitmap src, String watermark) {
        //get source image width and height
        int w = src.getWidth();
        int h = src.getHeight();

        Bitmap result = Bitmap.createBitmap(w, h, src.getConfig());
        Canvas canvas = new Canvas(result);
        canvas.drawBitmap(src, 0, 0, null);
        Paint paint = new Paint();
        Paint.FontMetrics fm = new Paint.FontMetrics();
        paint.setColor(Color.WHITE);
        paint.getFontMetrics(fm);
        int margin = 5;
        canvas.drawRect(50 - margin, 50 + fm.top - margin,
                50 + paint.measureText(watermark) + margin, 50 + fm.bottom
                        + margin, paint);

        paint.setColor(Color.RED);

        canvas.drawText(watermark, 50, 50, paint);
        return result;
    }

// 从 URI 中获取位图：

  private Bitmap getBitmapFromUri(String photoPath) {
        Bitmap image = null;
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        Bitmap bitmap = BitmapFactory.decodeFile(photoPath, options);
        return bitmap;
    }

// 保存图片 ：

 private String SaveImage(Bitmap finalBitmap) {

        String root = Environment.getExternalStorageDirectory().toString();
        File myDir = new File(root + "/shareImage");
        myDir.mkdirs();
        Random generator = new Random();
        int n = 10000;
        n = generator.nextInt(n);
        String fname = "Image" + n + ".jpg";

        File file = new File(myDir, fname);
        if (file.exists()) file.delete();
        try {
            FileOutputStream out = new FileOutputStream(file);
            finalBitmap.compress(Bitmap.CompressFormat.JPEG, 20, out);
            out.flush();
            out.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
        return file.getAbsolutePath();
    }

// 像这样调用：

                Bitmap bitmap = getBitmapFromUri(attachment.get(i).getPath()); // Enter here your Image path

                Bitmap bitmapp = waterMark(bitmap, "ENTER YOUR TEXT FOR WATERMARK LABEL");

                String path = SaveImage(bitmapp);
                Uri uri = Uri.fromFile(new File(path));

最后从 uri 你可以得到一个新的水印图像。

希望这对你有帮助。

Answer 3

我相信这个解决方案比drawPath.

用它来计算文本背景的大小：

private @NonNull Rect getTextBackgroundSize(float x, float y, @NonNull String text, @NonNull TextPaint paint) {
    Paint.FontMetrics fontMetrics = paint.getFontMetrics();
    float halfTextLength = paint.measureText(text) / 2 + 5;
    return new Rect((int) (x - halfTextLength), (int) (y + fontMetrics.top), (int) (x + halfTextLength), (int) (y + fontMetrics.bottom));
}

然后将背景绘制为Rect：

Rect background = getTextBackgroundSize(x, y, text, textPaint);
canvas.drawRect(background, bkgPaint);
canvas.drawText(text, x, t, textPaint);