如何在绘制时旋转从资源加载的Drawable
?例如,我想要绘制一个箭头,并且能够在绘制时将其旋转到不同方向。
发布于 2011-01-22 05:19:36
您需要使用Bitmap和Canvas类函数来准备drawable:
Bitmap bmpOriginal = BitmapFactory.decodeResource(this.getResources(), R.drawable.image2);
Bitmap bmResult = Bitmap.createBitmap(bmpOriginal.getWidth(), bmpOriginal.getHeight(), Bitmap.Config.ARGB_8888);
Canvas tempCanvas = new Canvas(bmResult);
tempCanvas.rotate(90, bmpOriginal.getWidth()/2, bmpOriginal.getHeight()/2);
tempCanvas.drawBitmap(bmpOriginal, 0, 0, null);
mImageView.setImageBitmap(bmResult);
在此代码中,示例将图像中心旋转90度。
发布于 2011-08-11 15:56:17
从本质上讲,它可以归结为:进行(n逆)画布变换,而不是变换drawable
private BitmapDrawable drawable; // or Drawable
protected void onDraw(Canvas canvas) { // inherited from View
//...
canvas.save();
canvas.rotate(degrees, pivotX, pivotY);
drawable.draw(canvas);
canvas.restore();
//...
}
如果使用BitmapDrawable,则可能需要通过设置抗锯齿来提高输出质量
drawable.setAntialias(true);
发布于 2016-06-01 22:26:08
可接受的答案对我不起作用。我有非正方形的图像,所以我对他的代码做了一些修改。
private Bitmap rotateDrawable(@DrawableRes int resId) {
Bitmap bmpOriginal = BitmapFactory.decodeResource(getResources(), resId);
Bitmap bmpResult = Bitmap.createBitmap(bmpOriginal.getHeight(), bmpOriginal.getWidth(), Bitmap.Config.ARGB_8888);
Canvas tempCanvas = new Canvas(bmpResult);
int pivot = bmpOriginal.getHeight() / 2;
tempCanvas.rotate(90, pivot, pivot);
tempCanvas.drawBitmap(bmpOriginal, 0, 0, null);
return bmpResult;
}
mImageView.setImageBitmap(rotateDrawable(R.drawable.some_image));
https://stackoverflow.com/questions/4763103
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