先看下实现效果
device-2018-05-18-111253.gif
对于自定义view不规则区域的触摸事件点击响应涉及的知识点
1.Region
2.Matrix坐标系变换
拓展知识点：3.Path绘图
Region
Region是绘制中的区域，是一个闭合的区域。使用Region可以取区域的交集或者并集最后得到我们的不规则区域。
Region的构造方法有
public Region()
public Region(Region region)
public Region(Rect r)
public Region(int left, int top, int right, int bottom)
Region也可以后期添加区域
public void setEmpty() //清空
public boolean set(Region region)
public boolean set(Rect r)
public boolean set(int left, int top, int right, int bottom)
public boolean setPath(Path path, Region clip)//将path和clip的两个区域取交集
对于上述的不规则区域,我们可以取一张屏幕画布和该不规则区域的path取交集,这样就能得到我们想要获得的区域了。
circleRegion = new Region();
path = new Path();
//Path.Direction.CW---顺时针 Path.Direction.CCW逆时针
path.addCircle(width / 2, height / 2, 250, Path.Direction.CW);
Region region = new Region(0, 0, width, height);
circleRegion.setPath(path, region);
可以使用
//绘制
RegionIterator iterator = new RegionIterator(region);
Rect rect = new Rect();
while (iterator.next(rect)) {
canvas.drawRect(rect, mPaint);
}
遍历我们得到的region区域。
知道了region概念后，我们可以对一个圆形图案的触摸坐标判断是否在圆形区域内。
image.png
public class AbsoluteMap extends View {
private Paint paint;
private int width, height;
private Path path;
private Region circleRegion;
public AbsoluteMap(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
private void init() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.BLUE);
paint.setStrokeWidth(10);
circleRegion = new Region();
path = new Path();
//Path.Direction.CW---顺时针 Path.Direction.CCW逆时针
path.addCircle(width / 2, height / 2, 250, Path.Direction.CW);
Region region = new Region(0, 0, width, height);
circleRegion.setPath(path, region);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = w;
height = h;
init();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawCircle(width / 2, height / 2, 250, paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (circleRegion.contains((int) event.getX(), (int) event.getY())) {
Toast.makeText(getContext(), "触摸区域内", Toast.LENGTH_LONG).show();
}
break;
}
return true;
}
}
可以看到，我们取出圆形region后，再对用户的触摸坐标getx,gety判断是否在区域内即可。
2.Matrix
image.png
从第一个例子可以看到我们用的是相对坐标系getx,gety来确定用户的触摸区域的，这样就存在一个问题，有时候开发者为了方便或者绘制的图形是对称图形时，我们会将坐标系平移，做出变换，这时候getx,gety就会发生变化。
所以一般我们会使用getRawX,getRawY来获取用户坐标，但是怎么把用户的绝对坐标转换成我们的画布坐标呢？
这里就需要了解一下Matrix了。
image.png
mapPoints mapRect mapVectors
这些API主要是根据当前Matrix矩阵对点、矩形区域和向量进行变换，以得到变换后的点、矩形区域和向量。经常和下面的invert方法结合使用。
invert
通过上面的mapXXX方法，可以获取变换后的坐标或者矩形。但假设我们知道了变换后的坐标，如何计算Matrix变换前的坐标那？！
此时通过invert方法获取的逆矩阵就派上用场了。所谓逆矩阵，就是Matrix旋转了30度，逆Matrix就反向旋转30度，Matrix放大n倍，逆Matrix就缩小n倍。
public class ChangeMap extends View {
private Paint paint;
private int width, height;
private Path path;
private Region circleRegion;
private Matrix matrix;
private float[] touchPoints = new float[2];
public ChangeMap(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
private void init() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.BLUE);
paint.setStrokeWidth(10);
circleRegion = new Region();
path = new Path();
//Path.Direction.CW---顺时针 Path.Direction.CCW逆时针
path.addCircle(0, 0, 250, Path.Direction.CW);
Region region = new Region(-width / 2, -height / 2, width / 2, height / 2);
circleRegion.setPath(path, region);
matrix = new Matrix();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = w;
height = h;
init();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.translate(width / 2, height / 2);
matrix.reset();
if (matrix.isIdentity()) {
canvas.getMatrix().invert(matrix);
}
canvas.drawPath(path, paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touchPoints[0] = event.getRawX();
touchPoints[1] = event.getRawY();
matrix.mapPoints(touchPoints);
if (circleRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "触摸区域内", Toast.LENGTH_LONG).show();
}
break;
}
return true;
}
}
明白了基本原理以后，我们就可以对复杂的不规则区域进行点击事件的判断了。
绘制第一张的图时，主要用到的就是path工具类。
public class SpecialMap extends View {
private Paint paint;
private int width, height;
private Region topRegion, leftRegion, rightRegion, bottomRegion, totalRegion, centerRegion;
private Matrix matrix;
private RectF rectFBig, rectFSmall;
private Path leftPath, topPath, rightPath, bottomPath, centerPath;
private float[] touchPoints = new float[2];
public SpecialMap(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
private void init() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.LTGRAY);
paint.setStrokeWidth(10);
topRegion = new Region();
leftRegion = new Region();
rightRegion = new Region();
bottomRegion = new Region();
totalRegion = new Region();
centerRegion = new Region();
rectFBig = new RectF(-400, -400, 400, 400);
rectFSmall = new RectF(-250, -250, 250, 250);
totalRegion = new Region(-width / 2, -height / 2, width / 2, height / 2);
leftPath = new Path();
topPath = new Path();
rightPath = new Path();
bottomPath = new Path();
centerPath = new Path();
int sweepAngle = 80;
/**
* startAngle是开始度数
* sweepAngle指的是旋转的度数，也就是以startAngle开始，旋转多少度，如果sweepAngle是正数，那么就是按顺时针方向旋转，如果是负数就是按逆时针方向旋转。
*/
rightPath.addArc(rectFBig, 5, sweepAngle);
/**
* arcTo是先画一个椭圆，然后再在这个椭圆上面截取一部分部形。这个图形自然就是一个弧线了
*/
rightPath.arcTo(rectFSmall, 5 + sweepAngle, -sweepAngle);
rightPath.close();
bottomPath.addArc(rectFBig, 95, sweepAngle);
bottomPath.arcTo(rectFSmall, 95 + sweepAngle, -sweepAngle);
bottomPath.close();
leftPath.addArc(rectFBig, 185, sweepAngle);
leftPath.arcTo(rectFSmall, 185 + sweepAngle, -sweepAngle);
leftPath.close();
topPath.addArc(rectFBig, 275, sweepAngle);
topPath.arcTo(rectFSmall, 275 + sweepAngle, -sweepAngle);
topPath.close();
centerPath.addCircle(0, 0, 120, Path.Direction.CW);
matrix = new Matrix();
leftRegion.setPath(leftPath, totalRegion);
topRegion.setPath(topPath, totalRegion);
rightRegion.setPath(rightPath, totalRegion);
bottomRegion.setPath(bottomPath, totalRegion);
centerRegion.setPath(centerPath, totalRegion);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width = w;
height = h;
init();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.translate(width / 2, height / 2);
matrix.reset();
if (matrix.isIdentity()) {
canvas.getMatrix().invert(matrix);
}
canvas.drawPath(leftPath, paint);
canvas.drawPath(bottomPath, paint);
canvas.drawPath(rightPath, paint);
canvas.drawPath(topPath, paint);
canvas.drawPath(centerPath, paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touchPoints[0] = event.getRawX();
touchPoints[1] = event.getRawY();
matrix.mapPoints(touchPoints);
if (topRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "点击了右上部", Toast.LENGTH_LONG).show();
} else if (leftRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "点击了左上部", Toast.LENGTH_LONG).show();
} else if (bottomRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "点击了左下部", Toast.LENGTH_LONG).show();
} else if (rightRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "点击了右下部", Toast.LENGTH_LONG).show();
} else if (centerRegion.contains((int) touchPoints[0], (int) touchPoints[1])) {
Toast.makeText(getContext(), "点击了中部", Toast.LENGTH_LONG).show();
}
break;
}
return true;
}
}
