java - Android，创建自定义 ImageView 形状

Question

我需要创建一个在运行时填充动态颜色的 View 。我已经完成了这项任务，但是实际 View 需要在右侧有一个“峰值”。通常，ImageView 仅是正方形或矩形。有谁知道我如何完成在 View 中添加三角形峰？

例如:

Answer 1

您可以重写 ImageView 的 onDraw 事件，并对 canvas 对象执行任何您需要的操作。

    public class MyImageView extends ImageView {
        ...
        @Override
        public void onDraw(Canvas canvas){
            super.onDraw(canvas);
            Point[] point = ... //create three points here for the triangle
            Paint paint = ... // create your desired color
            drawTriangle(canvas, point, paint);
    }

对于三角形绘制(参见this SO answer):

private void drawTriangle(Canvas canvas, Point[] point,  Paint paint) {

    float [] points  = new float[8];             
    points[0] = point[0].x;      
    points[1] = point[0].y;      
    points[2] = point[1].x;      
    points[3] = point[1].y;         
    points[4] = point[2].x;      
    points[5] = point[2].y;              
    points[6] = point[0].x;      
    points[7] = point[0].y;

    canvas.drawVertices(VertexMode.TRIANGLES, 8, points, 0, null, 0, null, 0, null, 0, 0, paint);
    Path path = new Path();
    path.moveTo(point[0].x , point[0].y);
    path.lineTo(point[1].x,point[1].y);
    path.lineTo(point[2].x,point[2].y);
    canvas.drawPath(path,paint);    
}