package com.mcxtzhang.cstviewdemo.matrix;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import com.mcxtzhang.cstviewdemo.R;
public class BitmapMashView extends View {
//将水平和竖直方向上都划分为20格
private final int WIDTH = 20;
private final int HEIGHT = 20;
private final int COUNT = (WIDTH + 1) * (HEIGHT + 1); //记录该图片包含21*21个点
private final float[] verts = new float[COUNT * 2]; //扭曲前21*21个点的坐标
private final float[] orig = new float[COUNT * 2]; //扭曲后21*21个点的坐标
private Bitmap mBitmap;
private float bH, bW;
public BitmapMashView(Context context) {
this(context, null);
}
public BitmapMashView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public BitmapMashView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
private void init() {
mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.flower);
bH = mBitmap.getWidth();
bW = mBitmap.getHeight();
int index = 0;
//初始化orig和verts数组。
for (int y = 0; y <= HEIGHT; y++) {
float fy = bH * y / HEIGHT;
for (int x = 0; x <= WIDTH; x++) {
float fx = bW * x / WIDTH;
orig[index * 2 + 0] = verts[index * 2 + 0] = fx;
orig[index * 2 + 1] = verts[index * 2 + 1] = fy;
index += 1;
}
}
//设置背景色
setBackgroundColor(Color.WHITE);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmapMesh(mBitmap, WIDTH, HEIGHT, verts
, 0, null, 0, null);
}
//工具方法,用于根据触摸事件的位置计算verts数组里各元素的值
private void warp(float cx, float cy) {
for (int i = 0; i < COUNT * 2; i += 2) {
float dx = cx - orig[i + 0];
float dy = cy - orig[i + 1];
float dd = dx * dx + dy * dy;
//计算每个座标点与当前点(cx、cy)之间的距离
float d = (float) Math.sqrt(dd);
//计算扭曲度,距离当前点(cx、cy)越远,扭曲度越小
float pull = 80000 / ((float) (dd * d));
//对verts数组(保存bitmap上21 * 21个点经过扭曲后的座标)重新赋值
if (pull >= 1) {
verts[i + 0] = cx;
verts[i + 1] = cy;
} else {
//控制各顶点向触摸事件发生点偏移
verts[i + 0] = orig[i + 0] + dx * pull;
verts[i + 1] = orig[i + 1] + dy * pull;
}
}
//通知View组件重绘
invalidate();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//调用warp方法根据触摸屏事件的座标点来扭曲verts数组
warp(event.getX(), event.getY());
return true;
}
}