在 Android 中旋转可绘制对象 [英] Rotating a drawable in Android

问题描述

从资源加载的 Drawable 如何在绘制时旋转?比如我想画一个箭头，画的时候能不能旋转成面向不同的方向?

How can a Drawable loaded from a resource be rotated when it is drawn? For example, I would like to draw an arrow and be able to rotate it to face in different directions when it is drawn?

推荐答案

需要使用Bitmap和Canvas Class函数来准备drawable:

You need to use Bitmap and Canvas Class functions to prepare 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);

在此代码示例中，图像中心发生了 90 度旋转.

In this code sample rotation for 90 degrees over image center occurs.

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