I have already set up the canvas for the drawing. My problem now is how to clear the drawing.
Tried doing this to no avail.
public void clear()
{
circlePath.reset();
mPath.reset();
// Calls the onDraw() method
//invalidate();
}
Please take a look at the whole code here:
https://gist.github.com/akosijiji/a29cca90bead2e5e35ad
Any help is truly appreciated.
点击按钮
b1.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
dv.clear(); // call clear method using in your custom view
}
});
在自定义视图中定义明确的方法
public void clear()
{
mBitmap = Bitmap.createBitmap(width,height ,
Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
//Added later..
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
invalidate();
}
重置所有绘图工具并调用 invalidate 以刷新视图。
完整的工作代码
public class MainActivity extends Activity implements ColorPickerDialog.OnColorChangedListener {
DrawingView dv ;
RelativeLayout rl;
private Paint mPaint;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dv = new DrawingView(this);
setContentView(R.layout.activity_main);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
rl = (RelativeLayout) findViewById(R.id.rl);
rl.addView(dv);
Button b = (Button) findViewById(R.id.button1);
//b.setText(R.string.France);
Button b1 = (Button) findViewById(R.id.button2);
rl.setDrawingCacheEnabled(true);
b.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// dv.clear();
new ColorPickerDialog(MainActivity.this, MainActivity.this, mPaint.getColor()).show();
}
});
b1.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
dv.clear();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public class DrawingView extends View {
private int width;
private int height;
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
Context context;
private Paint circlePaint;
private Path circlePath;
public DrawingView(Context c) {
super(c);
context=c;
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
circlePaint = new Paint();
circlePath = new Path();
circlePaint.setAntiAlias(true);
circlePaint.setColor(Color.BLUE);
circlePaint.setStyle(Paint.Style.STROKE);
circlePaint.setStrokeJoin(Paint.Join.MITER);
circlePaint.setStrokeWidth(4f);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
width =w;
height =h;
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
public void clear()
{
mBitmap = Bitmap.createBitmap(width,height ,
Bitmap.Config.ARGB_8888);
//Log.d("BITMAP","Restoring...");
//mBitmap=BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
mCanvas = new Canvas(mBitmap);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
//Added later..
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.GREEN);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
canvas.drawPath(circlePath, circlePaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
circlePath.reset();
circlePath.addCircle(mX, mY, 30, Path.Direction.CW);
// invalidate();
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
circlePath.reset();
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
// mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SCREEN));//.Mode.SCREEN));
mPaint.setMaskFilter(null);
mCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.SCREEN);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
@Override
public void colorChanged(int color) {
// TODO Auto-generated method stub
mPaint.setColor(color);
}
}
以上工作，但它不是一个好的设计，因为每次你需要清除你将创建像油漆对象这样的对象。
您可以创建单例类并重置您的工具，然后调用 invalidate
public class DrawingManager {
private static DrawingManager mInstance=null;
public DrawingTools mDrawingUtilities=null;
public int mThemeIndex;
public Canvas mCanvas;
public Path mPath;
public Paint mBitmapPaint;
public Bitmap mBitmap;
public Paint mPaint;
private DrawingManager()
{
resetDrawingTools();
}
public static DrawingManager getInstance()
{
if(mInstance==null)
{
mInstance=new DrawingManager();
}
return mInstance;
}
public void resetDrawingTools()
{
mBitmap = Bitmap.createBitmap(screenwidth,screenheight ,
Bitmap.Config.ARGB_8888)
mCanvas = new Canvas(mBitmap);
Path = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
//Added later..
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.Green);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(12);
}
/**
* Clears the drawing board.
*/
public static void clearDrawingBoard()
{
mInstance=null;
}
public void resetBitmapCanvasAndPath() {
// TODO Auto-generated method stub
mBitmap = Bitmap.createBitmap(screenwidth,screenheight ,
Bitmap.Config.ARGB_8888);
//Log.d("BITMAP","Restoring...");
//mBitmap=BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
mCanvas = new Canvas(.mBitmap);
mPath = new Path();
}
}
在你的绘画课上
private DrawingManager mDrawingManager=null;
mDrawingManager=DrawingManager.getInstance();// initialize drawing tools once
然后在按钮上单击以清除绘制
mDrawingManager.resetBitmapCanvasAndPath();
invalidate();
你应该使用 yourpaintlayout.removeallviews();
您会在绘图画布类中添加一种布局。您可以选择从图纸布局中删除所有视图。希望这会帮助你。