java - 在图像上写入文本时出错

Question

我尝试在图像上写文字:

private Bitmap drawText() {
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
             R.drawable.test); 

    Canvas canvas = new Canvas(bitmap);
    Paint paint = new Paint();
    paint.setColor(Color.BLACK);
    paint.setTextSize(5);
    canvas.drawText("Some Text here", 5, 5, paint);

    Bitmap resBitmap = Bitmap.createBitmap(canvas.getWidth(),
            canvas.getHeight(), Config.RGB_565);
    canvas.setBitmap(resBitmap);
    return resBitmap;

}

结果是一个全黑的图像。我做错了什么？

Answer 1

免责声明:我不是 Android 开发人员。我从来没有写过这样的代码。这只是我对文档的解释...

我怀疑您实际上想要将位图设置为更早地绘制，然后将另一个位图绘制到 Canvas 中。所以类似:

private Bitmap drawText() {
    // Load the existing image to get some dimensions
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
        R.drawable.test); 

    // Create a result bitmap and a canvas which draws onto it
    Bitmap resBitmap = Bitmap.createBitmap(bitmap.getWidth(),
        bitmap.getHeight(), Config.RGB_565);
    Canvas canvas = new Canvas(resBitmap);

    // Draw the existing image into the canvas
    canvas.drawBitmap(bitmap, 0f, 0f, null);

    // Draw text on top
    Paint paint = new Paint();
    paint.setColor(Color.BLACK);
    paint.setTextSize(5);
    canvas.drawText("Some Text here", 5, 5, paint);

    return resBitmap;
}