Drawing a filled rectangle with a border in androi

问题:

Is there any way in Android to draw a filled rectangle with say a black border. My problem is that the canvas.draw() takes one paint object, and to my knowledge the paint object can't have a different color for the fill and the stroke. Is there a way around this?

回答1:

You draw a rectangle with the color of the border and the size of the rectangle plus the border, you change the color of the paint and draw again the rectangle with the normal size.

回答2:

Try paint.setStyle(Paint.Style.FILL) and paint.setStyle(Paint.Style.STROKE).

Paint paint = new Paint();
Rect r = new Rect(10, 10, 200, 100);

@Override
public void onDraw(Canvas canvas) {
    // fill
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(Color.MAGENTA); 
    canvas.drawRect(r, paint);

    // border
    paint.setStyle(Paint.Style.STROKE);
    paint.setColor(Color.BLACK);
    canvas.drawRect(r, paint);
}

回答3:

If you are drawing multiple views then you could also use two paints, one for the stroke and one for the fill. That way you don't have to keep resetting them.

Paint fillPaint = new Paint();
Paint strokePaint = new Paint();

RectF r = new RectF(30, 30, 1000, 500);

void initPaints() {

    // fill
    fillPaint.setStyle(Paint.Style.FILL);
    fillPaint.setColor(Color.YELLOW);

    // stroke
    strokePaint.setStyle(Paint.Style.STROKE);
    strokePaint.setColor(Color.BLACK);
    strokePaint.setStrokeWidth(10);
}

@Override
protected void onDraw(Canvas canvas) {

    // First rectangle
    canvas.drawRect(r, fillPaint);    // fill
    canvas.drawRect(r, strokePaint);  // stroke

    canvas.translate(0, 600);

    // Second rectangle
    int cornerRadius = 50;
    canvas.drawRoundRect(r, cornerRadius, cornerRadius, fillPaint);    // fill
    canvas.drawRoundRect(r, cornerRadius, cornerRadius, strokePaint);  // stroke
}