版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/javaSXL/article/details/81708256
这段时间做了几个自定义控件，整理到博客上供大家参考，先看下画板效果图：
这个画板很简单，但基本的功能都具有了，橡皮擦，清除，撤销，反撤销，保存。想要实现更多的功能，比如说更改画笔颜色，大小等等功能，继续往上加代码就可以了。
实现这个画板的逻辑很简单，就是自定义一个画板控件，下面看下主要的代码：
public class DrawingBoardView extends View {
// 画图的模式（默认是画笔）
private DrawMode mDrawMode = DrawMode.PaintMode;
// 画笔
private Paint mPaint;
// 画笔颜色
private int mPaintColor = Color.RED;
// 画笔宽度
private int mPaintSize = diptopx(5);
// 橡皮擦的宽度
private int mEraserSize = diptopx(36);
// 缓冲的位图
private Bitmap mBufferBitmap;
// 缓冲的画布
private Canvas mBufferCanvas;
// 当前控件的宽
private int mWidth;
// 当前控件的高
private int mHight;
// 画布的颜色
private int mCanvasColor = Color.WHITE;
// 上次的位置
private float mLastX;
private float mLastY;
// 路径
private Path mPath;
// 设置图形混合模式为清除
private PorterDuffXfermode mEraserMode = new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);
// 保存的路径
private List<DrawPathInfo> savePaths;
// 当前的路径
private List<DrawPathInfo> currPaths;
// 最多保存20条路径
private int MAX_PATH = 20;
public DrawingBoardView(Context context) {
this(context, null);
}
public DrawingBoardView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public DrawingBoardView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initPath();
initPaint();
}
/**
* 初始化路径
*/
private void initPath() {
mPath = new Path();
savePaths = new ArrayList<DrawPathInfo>();
currPaths = new ArrayList<DrawPathInfo>();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mWidth = MeasureSpec.getSize(widthMeasureSpec);
mHight = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(mWidth, mHight);
initCanvas();
}
/**
* 初始化缓冲画布
*/
private void initCanvas() {
// 创建一个BITMAP
mBufferBitmap = Bitmap.createBitmap(mWidth, mHight, Bitmap.Config.ARGB_8888);
// 创建一个画布，所有mBufferCanvas画的东西都被保存在了mBufferBitmap中
mBufferCanvas = new Canvas(mBufferBitmap);
// 设置画布颜色
mBufferCanvas.drawColor(mCanvasColor);
}
/**
* 初始化画笔
*/
private void initPaint() {
// 设置画笔抗锯齿和抖动
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);
// 画笔只描边
mPaint.setStyle(Paint.Style.STROKE);
// 设置画笔颜色
mPaint.setColor(mPaintColor);
// 设置画笔宽度
mPaint.setStrokeWidth(mPaintSize);
// 设置圆形线帽
mPaint.setStrokeJoin(Paint.Join.ROUND);
// 设置线段连接处圆角
mPaint.setStrokeCap(Paint.Cap.ROUND);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(mBufferBitmap, 0, 0, null);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastX = x;
mLastY = y;
mPath.moveTo(mLastX, mLastY);
break;
case MotionEvent.ACTION_MOVE:
// 画出路径
mPath.quadTo(mLastX, mLastY, (mLastX + x) / 2, (mLastY + y) / 2);
mBufferCanvas.drawPath(mPath, mPaint);
invalidate();
mLastX = x;
mLastY = y;
break;
case MotionEvent.ACTION_UP:
// 保存路径
saveDrawPaths();
mPath.reset();
break;
}
return true;
}
/**
* 保存画的路径
*/
private void saveDrawPaths() {
if (savePaths.size() == MAX_PATH) {
savePaths.remove(0);
}
savePaths.clear();
savePaths.addAll(currPaths);
Path cachePath = new Path(mPath);
Paint cachePaint = new Paint(mPaint);
savePaths.add(new DrawPathInfo(cachePaint, cachePath));
currPaths.add(new DrawPathInfo(cachePaint, cachePath));
}
public int diptopx(float dipValue) {
final float scale = this.getResources().getDisplayMetrics().density;
return (int) (dipValue * scale + 0.5f);
}
/**
* 擦除画布
*/
public void clean() {
savePaths.clear();
currPaths.clear();
// 把位图擦成透明的
mBufferBitmap.eraseColor(Color.TRANSPARENT);
invalidate();
}
/**
* 设置画笔模式
*
* @param mode
*/
public void setMode(DrawMode mode) {
if (mode != mDrawMode) {
if (mode == DrawMode.EraserMode) {
mPaint.setStrokeWidth(mEraserSize);
mPaint.setXfermode(mEraserMode);
mPaint.setColor(mCanvasColor);
} else {
mPaint.setXfermode(null);
mPaint.setColor(mPaintColor);
mPaint.setStrokeWidth(mPaintSize);
}
mDrawMode = mode;
}
}
/**
* 获取当前模式
*
* @return
*/
public DrawMode getMode() {
return mDrawMode;
}
/**
* 上一步 撤销
*/
public void lastStep() {
if (currPaths.size() > 0) {
currPaths.remove(currPaths.size() - 1);
redrawBitmap();
}
}
/**
* 下一步 凡撤销
*/
public void nextStep() {
if (currPaths != savePaths) {
if (savePaths.size() > currPaths.size()) {
currPaths.add(savePaths.get(currPaths.size()));
redrawBitmap();
}
}
}
/**
* 重绘位图
*/
private void redrawBitmap() {
mBufferBitmap.eraseColor(Color.TRANSPARENT);
for (int i = 0; i < currPaths.size(); i++) {
DrawPathInfo path = currPaths.get(i);
mBufferCanvas.drawPath(path.getPath(), path.getPaint());
}
invalidate();
}
/**
* 保存图片
*/
public void save() {
mBufferCanvas.save(Canvas.ALL_SAVE_FLAG);
mBufferCanvas.restore();
String path = Environment.getExternalStorageDirectory().getPath();
//存储路径
File appDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
if (appDir == null) {
return;
}
String fileName = System.currentTimeMillis() + ".jpg";
File file = new File(appDir, fileName);
try {
FileOutputStream fileOutputStream = new FileOutputStream(file);
mBufferBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
fileOutputStream.close();
Toast.makeText(getContext(), "保存成功", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
e.printStackTrace();
}
}
}源码已上传到GitHub，欢迎fark,star点击查看GitHub源码