以編程方式創建圖標作爲ItemizedOverlay drawable使用 - Android

Question

我試圖以編程方式繪製一個停車圖標作爲地圖上的逐項疊加的可繪製位置。

該圖標由一個藍色方塊組成，其中央有一個白色「P」，我想以編程方式更改方塊的顏色以表示不同的停車類型。

我試着用drawRect & drawText創建它，但是我找不到一個簡單的將文本居中在正方形中的方法，我找不到一個將座標中心畫布的方法 - 它一直想要錨點從左上角開始。

我已經嘗試創建一個XML佈局來轉換爲drawable，但無法實現這一點。

有沒有一個優雅的解決方案，我試圖實現？

Answer 1

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; 
    } 
} 

Answer 2

做幾個PNG圖像&把它們放在res\drawable，如果你有比5色更多的顏色，那就考慮少用。這讓用戶感到困惑。