Question

我不知道如何将位图加载到画布中并在其上绘制。我尝试过，但是在位图上绘制不起作用，相反，它是在位图下绘制（我在后面看到了）。在此先感谢您，因为我是android新手，所以需要帮助。正常的绘图正常，并且单击“保存”按钮也可以保存该绘图。但是编辑不正常，我尝试但不正常。

public class DrawingView extends View {
public static int BRUSH_SIZE=18;
public static int ERASER_SIZE=25;
public static final int DEFAULT_COLOR= Color.BLACK;
public static final int DEFAULT_BG_COLOR= Color.WHITE;
private static final float TOUCH_TOLERANCE= 4;
private float pointX,pointY;
private Path path;
private Paint paint;
private ArrayList<FingerPath> pathsList = new ArrayList<>();
private ArrayList<FingerPath> redoList = new ArrayList<>();
private int currentColor;
private int backgroundColor=DEFAULT_BG_COLOR;
private int strokeWidth;
private Bitmap bitmap,bitmapToEdit,nBmp,canvasBitmap;
private Canvas canvas;
private Paint bitmapPaint = new Paint(Paint.DITHER_FLAG);
private int lastPath;
private boolean editMode;
Realm mRealm;
byte[] imgBytes; 

public DrawingView(Context context, AttributeSet attrs) {
    super(context, attrs);
    path=new Path();
    paint=new Paint();
    paint.setAntiAlias(true);
    paint.setDither(true);
    paint.setColor(DEFAULT_COLOR);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);
    paint.setStrokeCap(Paint.Cap.ROUND);
}

public void init(DisplayMetrics metrics){
    if(editMode)
        startNew();
    else {
        int height = metrics.heightPixels;
        int width = metrics.widthPixels;
        bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        canvas = new Canvas(bitmap);
    }
    currentColor = DEFAULT_COLOR;
    strokeWidth = BRUSH_SIZE;
}

public void startNew(){
    canvas.drawColor(0, PorterDuff.Mode.CLEAR);
    nBmp=bitmapToEdit.copy(Bitmap.Config.ARGB_8888,true);
    canvas.drawBitmap(nBmp,0,0,paint);
    invalidate();
}

@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    Log.e("size changed","called");
    bitmapToEdit=Bitmap.createBitmap(w,h, Bitmap.Config.ARGB_8888);
    canvasBitmap=Bitmap.createBitmap(w,h, Bitmap.Config.ARGB_8888);
    nBmp=Bitmap.createBitmap(w,h, Bitmap.Config.ARGB_8888);
    canvas=new Canvas(canvasBitmap);

}

public void editImage(Bitmap gotbitmap){
    editMode=true;
    bitmapToEdit=gotbitmap;
}

public void save(Context context){
    setDrawingCacheEnabled(true);
    Bitmap saveBitmap=getDrawingCache();
    imgBytes=new byte[0];
    mRealm=Realm.getDefaultInstance();
    if(saveBitmap!=null) {
        ByteArrayOutputStream stream=new ByteArrayOutputStream();
        saveBitmap.compress(Bitmap.CompressFormat.WEBP,50,stream);
        imgBytes=stream.toByteArray();
        final Drawing drawingObj=new Drawing();
        mRealm.executeTransaction(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                Number currentNum=mRealm.where(Drawing.class).maximumInt("id");
                Log.e("currentNum",String.valueOf(currentNum));
                int nextId;
                if(currentNum==null){
                    nextId=1;
                }else{
                    nextId=currentNum.intValue()+1;
                }
                Log.e("nextId",String.valueOf(nextId));
                drawingObj.setId(nextId);
                drawingObj.setImage(imgBytes);
                mRealm.copyToRealmOrUpdate(drawingObj);
                Log.e("imgBytes",imgBytes.toString());
            }
        });
        Toast.makeText(context,"Image saved Successfully",Toast.LENGTH_LONG).show();
        destroyDrawingCache();
    }else{
        Toast.makeText(context,"Image not found",Toast.LENGTH_LONG).show();
    }
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if(editMode){
        canvas.drawBitmap(canvasBitmap,0,0,bitmapPaint);
        canvas.drawPath(path,paint);
    }else {
        canvas.save();
        canvas.drawColor(backgroundColor);
        for (FingerPath fp : pathsList) {
            paint.setColor(fp.color);
            paint.setStrokeWidth(fp.strokeWidth);
            canvas.drawPath(fp.path, paint);
        }
        canvas.drawBitmap(bitmap, 0, 0, bitmapPaint);
        canvas.restore();
    }
}

//This function used when initial touch on screen
private void touchStart(float x,float y){
    redoList.clear();
    path = new Path();
    FingerPath fingerPath = new FingerPath(currentColor,strokeWidth,path);
    pathsList.add(fingerPath);
    path.reset();
    path.moveTo(x,y);
    pointX=x;
    pointY=y;
}

//This function used when keeping finger down and moving on screen
private void touchMove(float x,float y){
    float dx = Math.abs(x - pointX);
    float dy = Math.abs(y - pointY);
    if(dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE){
        path.quadTo(pointX,pointY,(x + pointX)/2,(y + pointY)/2);
        pointX=x;
        pointY=y;
    }
}

//This function used when after drawing, finger is removed from the screen
private void touchUp(){
    path.lineTo(pointX,pointY);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    if(editMode){
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(x,y);
                break;

            case MotionEvent.ACTION_MOVE:
                path.lineTo(x,y);
                break;

            case MotionEvent.ACTION_UP:
                canvas.drawPath(path,paint);
                path.reset();
                break;
        }
        invalidate();
    }
    else{
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touchStart(x, y);
                invalidate();
                break;

            case MotionEvent.ACTION_MOVE:
                touchMove(x, y);
                invalidate();
                break;

            case MotionEvent.ACTION_UP:
                touchUp();
                invalidate();
                break;
        }
    }
    return true;
}
}

Answer 1

如果editMode为false，则在绘制路径之后绘制位图。这将把位图放在最上面。要解决此问题，请将canvas.drawBitmap()呼叫放在canvas.drawColor(backgroundColor)呼叫之后：）

如何将位图加载到画布中并用手指在位图上自由绘制？

1 个答案: