Android绘制时仅使用图像擦除颜色，而不使用背景图像

Android绘制时仅使用图像擦除颜色，而不使用背景图像

我有一个相对布局，其中图像设置为其

android:background=“@mipmap/ic_launcher”

然后是一个线性布局，我们可以在上面画各种颜色 用橡皮擦我们可以清除颜色，效果很好

使用

MotionEvent.ACTION\u MOVE:

颜色会立即用

此函数

public void setErase(boolean isErase){
        //set erase true or false
        if(isErase){
            drawPaint.setAlpha(0xFF);
            drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));


        }
        else {
            drawPaint.setXfermode(null);
        }
}

问题是Bakground图像也会被擦除

与

图像被重置，我们在RelativeLayout中返回图像

我只想用

MotionEvent.ACTION\u MOVE

擦除颜色，而不是图像

我已经提到这一点

代码是

用于自定义视图

public class CustomView extends View {

    //drawing path
    private Path drawPath;
    //drawing and canvas paint
    private Paint drawPaint, canvasPaint;
    //initial color
    private int paintColor = 0xFF660000;
    //canvas
    private Canvas drawCanvas;
    //canvas bitmap
    private Bitmap canvasBitmap;

    private float brushSize, lastBrushSize;

    private  int width, height;

    //comment to attached on the image
    private  String comment;

    public CustomView(Context context, AttributeSet attrs ){
        super(context, attrs);
        setupDrawing();
    }

    private void setupDrawing(){
        //get drawing area setup for interaction
        drawPath = new Path();
        drawPaint = new Paint();

        brushSize = getResources().getInteger(R.integer.medium_size);
        lastBrushSize = brushSize;

        //initialize drawPaint
        drawPaint.setColor(paintColor);

        //initialize drawPath
        drawPaint.setAntiAlias(true);
        drawPaint.setStrokeWidth(brushSize);
        drawPaint.setStyle(Paint.Style.STROKE);
        drawPaint.setStrokeJoin(Paint.Join.ROUND);
        drawPaint.setStrokeCap(Paint.Cap.ROUND);

        canvasPaint = new Paint(Paint.DITHER_FLAG);

        //drawCanvas.drawText("test", 20, 20, null);
    }

    public void setImageBitmap(Bitmap bmp){
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setFilterBitmap(true);
        paint.setDither(true);

        /*
        * */
        int bmp_width = bmp.getWidth();
        int bmp_height = bmp.getHeight();
        float scaleWidth = ((float) width) / bmp_width;
        float scaleHeight = ((float) height) / bmp_height;
        // CREATE A MATRIX FOR THE MANIPULATION
        Matrix matrix = new Matrix();
        // RESIZE THE BIT MAP
        matrix.postScale(scaleWidth, scaleHeight);

        // "RECREATE" THE NEW BITMAP
        Bitmap resizedBitmap = Bitmap.createBitmap(
                bmp, 0, 0, bmp_width, bmp_height, matrix, false);
        //

        drawCanvas.drawBitmap(resizedBitmap, 0, 0, paint);
        invalidate();
    }

    public void startNew(){
        drawCanvas.drawColor(0, PorterDuff.Mode.CLEAR);
        invalidate();
    }

    public void setComment(String commentText){
        this.comment = commentText;
    }

    public void setErase(boolean isErase){
        //set erase true or false
        if(isErase){
            drawPaint.setAlpha(0xFF);
            drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));


        }
        else {
            drawPaint.setXfermode(null);

        }
    }

    public void setBrushSize(float newSize){
        //update size

        brushSize= TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                newSize, getResources().getDisplayMetrics());

        drawPaint.setStrokeWidth(brushSize);
    }

    public void setLastBrushSize(float lastSize){
        lastBrushSize=lastSize;
    }
    public float getLastBrushSize(){
        return lastBrushSize;
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

        width = w;
        height = h;

        canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        drawCanvas = new Canvas(canvasBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
        canvas.drawPath(drawPath, drawPaint);
    }

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

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    if(!Objects.equals(comment, "") && comment != null ){
                        canvasPaint.setTextSize(60);
                        canvasPaint.setColor(paintColor);
                        drawCanvas.drawText(comment, touchX, touchY, canvasPaint);
                        comment = "";
                        return true;
                    }
                    else {
                        drawPath.moveTo(touchX, touchY);
                    }
                }
                break;
            case MotionEvent.ACTION_MOVE:
                drawPath.lineTo(touchX, touchY);
                break;
            case MotionEvent.ACTION_UP:
                drawCanvas.drawPath(drawPath, drawPaint);
                drawPath.reset();
                break;
            default:
                return false;
        }

        invalidate();
        return true;
    }

    public void setColor(String newColor){
        //set color
        invalidate();

        paintColor = Color.parseColor(newColor);
        drawPaint.setColor(paintColor);
    }

    public void setColor(int newColor){
        invalidate();
        drawPaint.setColor(newColor);
    }

}

布局是

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@mipmap/ic_launcher"

    >



<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation = "vertical"
    android:background="#00000000"
    tools:context=".MainActivity"
    android:id="@+id/main_activity">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:layout_gravity="center"
        android:orientation="horizontal" >
        <ImageButton
            android:id="@+id/new_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/new_pic"/>
        <ImageButton
            android:id="@+id/draw_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_brush"/>
        <ImageButton
            android:id="@+id/erase_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_eraser"/>
        <ImageButton
            android:id="@+id/save_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_save"/>
        <ImageButton
            android:id="@+id/takingPhoto_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/photo"
            android:src="@drawable/ic_camera"/>
        <ImageButton
            android:id="@+id/text_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/text"
            android:src="@drawable/ic_text"/>

    </LinearLayout>

    <com.rfachrur.gmbr.CustomView
        android:id="@+id/drawing"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_marginBottom="0dp"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="0dp"
        android:layout_weight="1"
        android:background="#00000000"
        android:layout_margin="0dp" />


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/select_img"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:text="@string/add_image"
            android:src="@drawable/ic_text"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:orientation="vertical" >

            <!-- Top Row -->
            <LinearLayout
                android:id="@+id/paint_colors"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal" >
                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF660000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF660000" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF0000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF0000" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF6600"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF6600" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFFCC00"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFFCC00" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF009900"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF009900" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF009999"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF009999" />
            </LinearLayout>
            <!-- Bottom Row -->
            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal" >
                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF0000FF"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF0000FF" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF990099"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF990099" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF6666"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF6666" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFFFFFF"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFFFFFF" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF787878"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF787878" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF000000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF000000" />
            </LinearLayout>
        </LinearLayout>

    </LinearLayout>
</LinearLayout>

</RelativeLayout>

---

我只想删除颜色而不是背景图像

这实际上解决了我的问题，非常易于使用和实现

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@mipmap/ic_launcher"

    >



<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation = "vertical"
    android:background="#00000000"
    tools:context=".MainActivity"
    android:id="@+id/main_activity">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:layout_gravity="center"
        android:orientation="horizontal" >
        <ImageButton
            android:id="@+id/new_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/new_pic"/>
        <ImageButton
            android:id="@+id/draw_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_brush"/>
        <ImageButton
            android:id="@+id/erase_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_eraser"/>
        <ImageButton
            android:id="@+id/save_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/start_new"
            android:src="@drawable/ic_save"/>
        <ImageButton
            android:id="@+id/takingPhoto_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/photo"
            android:src="@drawable/ic_camera"/>
        <ImageButton
            android:id="@+id/text_btn"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:contentDescription="@string/text"
            android:src="@drawable/ic_text"/>

    </LinearLayout>

    <com.rfachrur.gmbr.CustomView
        android:id="@+id/drawing"
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_marginBottom="0dp"
        android:layout_marginLeft="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginTop="0dp"
        android:layout_weight="1"
        android:background="#00000000"
        android:layout_margin="0dp" />


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/select_img"
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:text="@string/add_image"
            android:src="@drawable/ic_text"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:orientation="vertical" >

            <!-- Top Row -->
            <LinearLayout
                android:id="@+id/paint_colors"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal" >
                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF660000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF660000" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF0000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF0000" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF6600"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF6600" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFFCC00"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFFCC00" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF009900"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF009900" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF009999"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF009999" />
            </LinearLayout>
            <!-- Bottom Row -->
            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal" >
                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF0000FF"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF0000FF" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF990099"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF990099" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFF6666"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFF6666" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FFFFFFFF"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FFFFFFFF" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF787878"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF787878" />

                <ImageButton
                    android:layout_width="@dimen/large_brush"
                    android:layout_height="@dimen/large_brush"
                    android:layout_margin="2dp"
                    android:background="#FF000000"
                    android:contentDescription="@string/paint"
                    android:onClick="paintClicked"
                    android:src="@drawable/paint"
                    android:tag="#FF000000" />
            </LinearLayout>
        </LinearLayout>

    </LinearLayout>
</LinearLayout>

</RelativeLayout>