以编程方式创建用作ItemizedOverlay可绘制对象的图标-Android [英] Programmatically creating icon to use as ItemizedOverlay drawable - Android

问题描述

我试图以编程方式绘制一个停车图标，以将其作为可绘制对象放置在地图上的逐项叠加中.

I am trying to programmatically draw a parking icon to place as the drawable for an itemized overlay on a map.

该图标由一个蓝色正方形组成，中间带有白色"P"，我想以编程方式更改正方形的颜色，以表示不同的停车类型.

The icon consists of a blue square with a white 'P' in its centre of which I would like to programmatically change the colour of the square to denote different parking types.

我尝试使用drawRect&在画布上创建它. drawText，但是我找不到将文本居中于正方形的简单方法，也找不到将画布居中于坐标的方法-它一直想从左上角锚定.

I've tried creating it via the canvas using drawRect & drawText but I cannot find a simple way of centering the text in the square and I cannot find a way to center the canvas on the coordinates - it keeps wanting to anchor from the top left hand corner.

我也尝试创建XML布局以转换为可绘制对象，但也无法实现.

I've alternatively tried creating an XML layout to convert to a drawable but cannot achieve this either.

我要达到的目标是否有一个优雅的解决方案?

Is there an elegant solution for what I am trying to achieve?

推荐答案

public class TextDrawable extends Drawable {

    private final static int    TEXT_PADDING           = 3;
    private final static int    ROUNDED_RECT_RADIUS    = 5;

    private final String    text;
    private final Paint     textPaint;
    private final Rect      textBounds;
    private final Paint     bgPaint;
    private final RectF     bgBounds;

    public TextDrawable(String text, String backgroundColor, int textHeight) {

        this.text = text;

        // Text
        this.textPaint = new Paint();
        this.textBounds = new Rect();
        textPaint.setColor(Color.WHITE);
        textPaint.setARGB(255, 255, 255, 255);
        textPaint.setAntiAlias(true);
        textPaint.setSubpixelText(true);
        textPaint.setTextAlign(Paint.Align.CENTER); // Important to centre horizontally in the background RectF
        textPaint.setTextSize(textHeight);
        textPaint.setTypeface(Typeface.DEFAULT_BOLD);
        // Map textPaint to a Rect in order to get its true height
        // ... a bit long-winded I know but unfortunately getTextSize does not seem to give a true height!
        textPaint.getTextBounds(text, 0, text.length(), textBounds);

        // Background
        this.bgPaint = new Paint();
        bgPaint.setAntiAlias(true);
        bgPaint.setColor(Color.parseColor(backgroundColor));
        float rectHeight  = TEXT_PADDING * 2 + textHeight;
        float rectWidth   = TEXT_PADDING * 2 + textPaint.measureText(text);
        //float rectWidth   = TEXT_PADDING * 2 + textHeight;  // Square (alternative)
        // Create the background - use negative start x/y coordinates to centre align the icon
        this.bgBounds = new RectF(rectWidth / -2, rectHeight / -2, rectWidth / 2, rectHeight / 2);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawRoundRect(bgBounds, ROUNDED_RECT_RADIUS, ROUNDED_RECT_RADIUS, bgPaint);
        // Position the text in the horizontal/vertical centre of the background RectF
        canvas.drawText(text, 0, (textBounds.bottom - textBounds.top)/2, textPaint);
    }

    @Override
    public void setAlpha(int alpha) {
        bgPaint.setAlpha(alpha);
        textPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        bgPaint.setColorFilter(cf);
        textPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}

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