Android(安卓)Canvas 旋转Rect功能实施
16lz
2021-01-26
旋转方框功能实现图解
代码实现 1.采用矩阵映射,得到旋转后的功能按钮的新坐标(旋转按钮,删除按钮,缩放按钮)
//检测点击是否在范围 getTouchRect(rotateRect).contains(x1, y1); //得到旋转后按钮点击事件框 public RectF getTouchRect(RectF rect){// System.out.println("处理触摸事件。。。。"); if(matrix==null){ return rect; } matrix.mapRect(tempRect,rect); return tempRect; }
2.计算角度
判断三点是顺时针还是逆时针方向 资料:http://blog.sina.com.cn/s/blog_631f9e4b0100g874.html 已知三点求 三点之间夹角角度 资料:http://blog.csdn.net/lilin8905/article/details/69373069
public static double calcAngle(Point cen, Point first, Point second) { final double M_PI = 3.1415926535897 ; double ma_x = first.x - cen.x; double ma_y = first.y - cen.y; double mb_x = second.x - cen.x; double mb_y = second.y - cen.y; double v1 = (ma_x * mb_x) + (ma_y * mb_y); double ma_val = Math.sqrt(ma_x * ma_x + ma_y * ma_y); double mb_val = Math.sqrt(mb_x * mb_x + mb_y * mb_y); double cosM = v1 / (ma_val * mb_val); double angleAMB = Math.acos(cosM) * 180 / M_PI; int v=(cen.x-first.x)*(second.y-cen.y)-(cen.y-first.y)*(second.x-cen.x); if(v>0){// System.out.println("逆时针"); return -angleAMB; }else if(v<0){// System.out.println("顺时针"); }else{// System.out.println("不变"); } return angleAMB; }
3.绘制图形
@Override
public void onDraw(Canvas canvas) { canvas.save(); canvas.rotate(degree,rect.left+(rect.right-rect.left)/2,rect.top+(rect.bottom-rect.top)/2); //以矩形中心点旋转图形 canvas.drawRect(rect, paint); if(isEdit){ canvas.drawBitmap(deleteIcon, deleteRect.left, deleteRect.top, paint); canvas.drawBitmap(resizeIcon, resizeRect.left, resizeRect.top, paint); canvas.drawBitmap(rotateIcon, rotateRect.left, rotateRect.top, paint); } canvas.restore(); }
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