手写app学习笔记（二）

实现手写的view：

public class DrawView extends View {

Paint mPaint;// 画笔
Path path;// 路径
Bitmap cacheBitmap;// 缓存位图
Canvas cacheCanvas;// 缓存画布

// private int clr_bg, clr_fg;

public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);

// clr_bg = Color.WHITE;
// clr_fg = Color.CYAN;
// 初始化画笔
mPaint = new Paint();
// Dither（图像的抖动处理，当每个颜色值以低于8位表示时，对应图像做抖动处理可以实现在可显示颜色总数比较低（比如256色）时还保持较好的显示效果：
mPaint.setDither(true);
mPaint.setAntiAlias(true);// 抗锯齿
mPaint.setStyle(Paint.Style.STROKE);// 画轮廓
mPaint.setStrokeWidth(3);// 线条宽度
mPaint.setAlpha(255);

path = new Path();
// 创建位图、画布，绘底色
cacheBitmap = Bitmap.createBitmap(480, 800, Config.ARGB_8888);
cacheCanvas = new Canvas(cacheBitmap);

photoPath=new Path();
}

public DrawView(Context context) {
super(context);
}

/**
* invalidate时候会调用
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 绘制上一次，否则不连贯
// canvas.
// 因为手指抬起后会重置path,所以需要先绘制上次保存的状态
canvas.drawBitmap(cacheBitmap, 0, 0, null);
// 绘制路径
canvas.drawPath(path, mPaint);
}

/**
* 清空画布
*/
public void clear() {
// 清屏
Paint p = new Paint();
p.setXfermode(new PorterDuffXfermode(Mode.CLEAR));
cacheCanvas.drawPaint(p);
// p.setXfermode(new PorterDuffXfermode(Mode.SRC));
// path.reset();
// cacheBitmap = Bitmap.createBitmap(480, 800, Config.ARGB_8888);
// cacheCanvas.drawColor(clr_bg);
// cacheCanvas.drawColor(Color.TRANSPARENT);
photoPath.reset();
invalidate();
}

private float curX, curY;
public boolean isMoving;

Path photoPath;
float top=0.0f;
float left=0.0f;
float scale=1.0f;
float Dx=0f;
float Dy=0f;
float picScale=1f;
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();

switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
curX = x;
curY = y;
path.moveTo(x, y);
isMoving = true;
photoPath.moveTo((left+x-Dx)/scale*picScale, (top+y-Dy)/scale*picScale);
// photoPath.moveTo(left+x, top+y);
// Log.i("按下", "坐标：("+x+","+y+")");
break;
case MotionEvent.ACTION_MOVE:
// if (!isMoving) {
// break;
// }
path.quadTo(curX, curY, x, y);
// Log.i("移动", "坐标：("+x+","+y+")");
// 效果一样的方法
// path.lineTo(x, y);
photoPath.quadTo((left+curX-Dx)/scale*picScale, (top+curY-Dy)/scale*picScale,(left+x-Dx)/scale*picScale, (top+y-Dy)/scale*picScale);
// photoPath.quadTo(left+curX, top+curY,left+x, top+y);
curX = x;
curY = y;

break;
case MotionEvent.ACTION_UP:
// 保存最后的状态
cacheCanvas.drawPath(path, mPaint);
// 重置画笔
path.reset();
// Log.i("提起", "坐标：("+(left+x/scale)+","+(top+y/scale)+")");
isMoving = false;
break;
default:
break;
}
invalidate();
return true;
}

/**
* 保存图片方法
*
* @param filename
*/
public void saveToFile(String filename) throws FileNotFoundException {
File file = new File(filename);
if (file.exists()) {
throw new RuntimeException("文件:" + filename + "已经存在");
}
FileOutputStream fos = new FileOutputStream(new File(filename));
cacheBitmap.compress(CompressFormat.PNG, 50, fos);
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* 设置参数
* @param top：上边距
* @param left：左边距
* @param scale：photo点击缩放比例
* @param Dx：横坐标偏移量
* @param Dy：纵坐标偏移量
* @param picScale:图片显示在photo上的缩放比例
*/
public void setPathPoint(float top,float left,float scale,float Dx,float Dy,float picScale){
this.top=-top;
this.left=-left;
this.scale=scale;
this.Dx=Dx;
this.Dy=Dy;
this.picScale=picScale;
Log.i("传入手写界面的参数", "坐标：("+-top+","+-left+");scale:"+scale+";Dx:"+Dx+";"+";Dy:"+Dy);
}

public Bitmap getPathBitmap() {
return cacheBitmap;
}

public Path getPhotoPath(){
return photoPath;
}

public Paint getPaint(){
return mPaint;
}