下面代码中的行 (A) 和行 (B) 应生成相同的图像。
然而,行 (A) 却产生了图像:
怎么了?光栅化后是否应用视图/画布转换?
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.view.View;
import android.graphics.Matrix;
public class MyView extends View {
Paint paint = new Paint();
public MyView(Context c) {
super(c);
// this.setLayerType(View.LAYER_TYPE_SOFTWARE, null); // (C)
}
Rect canvasRect = new Rect();
RectF canvasRectf = new RectF();
RectF scene = new RectF();
Matrix M = new Matrix();
@Override
protected void onDraw(Canvas canvas) {
getDrawingRect(canvasRect);
canvasRectf.set(canvasRect);
scene.set(0,0, 100,100); // (A)
// scene.set(0,0, 500,500); // (B)
M.setRectToRect(scene, canvasRectf, Matrix.ScaleToFit.CENTER);
canvas.setMatrix(M);
canvas.drawCircle( 50, 50, 1, paint); // (A)
// canvas.drawCircle(250,250, 5, paint); // (B)
}
}
更新:如果 (C) 行未注释,则不会出现问题(谢谢,Henry)。使用硬件加速时是否可以获得第一张图像?