如何在自定义视图中添加按钮？

Question

I'm going too build a painting application with some buttons. Now i want to add some buttons to that. my code as follows.

 package com.example.drawing;

    import android.os.Bundle;
    import android.app.Activity;
    import android.view.Menu;


    public class TouchActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SingleTouchEventView(this, null));
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_touch, menu);
        return true;
    }
    }


package com.example.drawing;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class SingleTouchEventView extends View {
    private Paint paint = new Paint();
    private Path path = new Path();

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

        paint.setAntiAlias(true);
        paint.setStrokeWidth(6f);
        paint.setColor(Color.RED);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawPath(path, paint);
    }

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

        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            path.moveTo(eventX, eventY);
            return true;
        case MotionEvent.ACTION_MOVE:
            path.lineTo(eventX, eventY);
            break;
        case MotionEvent.ACTION_UP:
            // nothing to do
            break;
        default:
            return false;
        }

        // Schedules a repaint.
        invalidate();
        return true;
    }
}

How can i add a button to this?. reffered some sites and some answers to questions in Stackoverflow ( link 1 link 2 ) But couldn't find an answer.

Answer 1

You can add a button programmatically or your custom view can inflate an xml. You add to this xml the buttons you want and you are still able to draw on the canvas.

Answer 2

Create a class GraphicsActivity like:

class GraphicsActivity extends Activity {

private static final boolean TEST_PICTURE = true;
int f=0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


}



@Override
public void setContentView(View view) {
    if (TEST_PICTURE) {

        if(f==0){
        ViewGroup vg = new PictureLayout(this);
        vg.addView(view);

        LayoutInflater inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View vi = inflater.inflate(R.layout.activity_main, vg);
        view = vg;
        }

    }



    super.setContentView(view);
}



/*@Override
public void onConfigurationChanged(Configuration newConfig) {
    // TODO Auto-generated method stub
    super.onConfigurationChanged(newConfig);
    if(newConfig.orientation==Configuration.ORIENTATION_PORTRAIT){
        f=0;
        }else{
         f=1;


        }

}*/

}

Create your activity_main and add necessary buttons on it. The following is your PictureLayout.java :

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Picture;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;

class PictureLayout extends ViewGroup {
    private final Picture mPicture = new Picture();

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

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

    @Override
    public void addView(View child) {
        if (getChildCount() > 1) {
            throw new IllegalStateException(
                    "PictureLayout can host only one direct child");
        }

        super.addView(child);
    }

    @Override
    public void addView(View child, int index) {
        if (getChildCount() > 1) {
            throw new IllegalStateException(
                    "PictureLayout can host only one direct child");
        }

        super.addView(child, index);
    }

    @Override
    public void addView(View child, LayoutParams params) {
        if (getChildCount() > 1) {
            throw new IllegalStateException(
                    "PictureLayout can host only one direct child");
        }

        super.addView(child, params);
    }

    @Override
    public void addView(View child, int index, LayoutParams params) {
        if (getChildCount() > 1) {
            throw new IllegalStateException(
                    "PictureLayout can host only one direct child");
        }

        super.addView(child, index, params);
    }

    @Override
    protected LayoutParams generateDefaultLayoutParams() {
        return new LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.MATCH_PARENT);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        final int count = getChildCount();

        int maxHeight = 0;
        int maxWidth = 0;

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                measureChild(child, widthMeasureSpec, heightMeasureSpec);
            }
        }

        maxWidth += getPaddingLeft() + getPaddingRight();
        maxHeight += getPaddingTop() + getPaddingBottom();

        Drawable drawable = getBackground();
        if (drawable != null) {
            maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
            maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
        }

        setMeasuredDimension(resolveSize(maxWidth, widthMeasureSpec),
                resolveSize(maxHeight, heightMeasureSpec));
    }

    private void drawPict(Canvas canvas, int x, int y, int w, int h, float sx,
            float sy) {
        canvas.save();
        canvas.translate(x, y);
        canvas.clipRect(0, 0, w, h);
        canvas.scale(0.5f, 0.5f);
        canvas.scale(sx, sy, w, h);
        canvas.drawPicture(mPicture);
        canvas.restore();
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(mPicture.beginRecording(getWidth(), getHeight()));
        mPicture.endRecording();

        int x = getWidth() / 2;
        int y = getHeight() / 2;

        if (true) {
            canvas.drawPicture(mPicture);
        } else {
            drawPict(canvas, 0, 0, x, y, 1, 1);
            //drawPict(canvas, x, 0, x, y, -1, 1);
            //drawPict(canvas, 0, y, x, y, 1, -1);
            //drawPict(canvas, x, y, x, y, -1, -1);
        }
    }

    @Override
    public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
        location[0] = getLeft();
        location[1] = getTop();
        dirty.set(0, 0, getWidth(), getHeight());
        return getParent();
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        final int count = super.getChildCount();

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                final int childLeft = getPaddingLeft();
                final int childTop = getPaddingTop();
                child.layout(childLeft, childTop,
                        childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());

            }
        }
    }
}

The above procedure should work.Your class should extend GraphicsActivity instead of Activity .

Answer 3

You just needed to extend ViewGroup rather than View for your custom view to add some child to it and add button to it dynamically as

SingleTouchEventView view = new SingleTouchEventView(this, null);

Button btn = new Button(this);
LayoutParams pars = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
btn.setLayoutParams(pars);
btn.setText("Hello World");
btn.setPadding(10, 10, 10, 10);
view.addView(btn);

setContentView(view);