Canvas与图层（三）恢复画布

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wx5ba8dc11102bc 2023-01-06 10:13:14 博主文章分类：Android自定义view ©著作权

文章标签 Android自定义动画 d3 System 出栈 文章分类 虚拟化云计算

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恢复画布有两个函数：restore()与rest无论哪种* 恢复画布有两个函数：restore()与restongoCount()
restore()就是把回退栈中的最上层画布状态出栈，恢复画布状态，具体使用
restoreToCount(int count)

public int save();
public int save(int saveFlags)
public int saveLayer(RectF bounds, Paint paint, int saveFlags)
public int saveLayer(float left, float top, float right, float bottom ,Paint paint, int saveFlags)
public int save:ayerAlpha(REctF bounds, int alpha, int saveFlags)
public int saveLayerAlpha(float left, float top ,float right, float bottom,  int alpha, int saveFlags);

在 save()、saveLayer()、saveLayerAlpha()函数保存画布后，都会返回一个ID值，这个ID值表示当前的画布的栈层索引（从0开始）。比如，保存在第三层，则返回2

//表示一直退栈，直到将指定索引的画布信息退出来，之后的栈的最上层的画布信息将作为最新的画布
public void restoreToCount(int saveCount);

eg：

public class RestoreToCountView extends View {
    private Paint paint;
    public RestoreToCountView(Context context,  AttributeSet attrs) {
        super(context, attrs);
        paint =  new Paint();
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int id1 = canvas.save();
        canvas.clipRect(0, 0, 800, 800);
        canvas.drawColor(Color.BLACK);
        System.out.println(id1);
        int id2 = canvas.saveLayer(0, 0, getWidth(), getHeight(), paint, Canvas.ALL_SAVE_FLAG);
        canvas.clipRect(100, 100, 700, 700);
        canvas.drawColor(Color.RED);
        System.out.println(id2);
        int id3 = canvas.saveLayerAlpha(0, 0, getWidth(),getHeight(), 0xf0, Canvas.ALL_SAVE_FLAG);
        canvas.clipRect(200, 200, 600, 600);
        canvas.drawColor(Color.YELLOW);
        System.out.println(id3);
        int id4 = canvas.save();
        canvas.clipRect(300, 300, 500, 500);
        canvas.drawColor(Color.BLUE);
        System.out.println(id4);
        //恢复到生成id3之前的画布状态
        canvas.restoreToCount(id3);
        canvas.drawColor(Color.GREEN);
    }
}