How to draw text on canvas?
我正在尝试为Android开发一个简单的饼图类。 目前，它可以绘制标签和值的地图并绘制饼图。 我还没有为饼图添加图例，这是我需要将文本放置在屏幕角落小矩形附近的位置。 任何帮助表示赞赏，因为我是Android开发人员的新手。
您将必须使用Canvas类的drawText方法。
1 2 3 4 5 | Paint paint = new Paint(); canvas.drawPaint(paint); paint.setColor(Color.BLACK); paint.setTextSize(16); canvas.drawText("My Text", x, y, paint); |
这是有关的相关文档：
http://developer.android.com/reference/android/graphics/Canvas.html#drawText(java.lang.String，float，float，android.graphics.Paint)
这里曾经有另一个答案被删除，因为它只是一个链接。原始链接在这里。代码基本相同，但是我取出了非文本绘图部分，并按比例放大了尺寸，以便在现代屏幕密度下更好地工作。
这仅显示了您可以使用文本绘图进行的一些操作。
这是更新的代码：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 | public class MainActivity extends AppCompatActivity { DemoView demoview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); demoview = new DemoView(this); setContentView(demoview); } private class DemoView extends View { public DemoView(Context context){ super(context); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); // custom drawing code here // remember: y increases from top to bottom // x increases from left to right int x = 0; int y = 0; Paint paint = new Paint(); paint.setStyle(Paint.Style.FILL); canvas.save(); canvas.translate(100, 200); // make the entire canvas white canvas.drawColor(Color.WHITE); // draw some text using STROKE style paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(1); paint.setColor(Color.MAGENTA); paint.setTextSize(100); canvas.drawText("Style.STROKE", 0, 0, paint); canvas.translate(0, 200); // draw some text using FILL style paint.setStyle(Paint.Style.FILL); //turn antialiasing on paint.setAntiAlias(true); //paint.setTextSize(30); canvas.drawText("Style.FILL", 0, 0, paint); canvas.translate(0, 200); // draw some rotated text // get text width and height // set desired drawing location x = 75; y = 185; paint.setColor(Color.GRAY); //paint.setTextSize(25); String str2rotate ="Rotated!"; // draw bounding rect before rotating text Rect rect = new Rect(); paint.getTextBounds(str2rotate, 0, str2rotate.length(), rect); canvas.translate(x, y); paint.setStyle(Paint.Style.FILL); // draw unrotated text canvas.drawText("!Rotated", 0, 0, paint); paint.setStyle(Paint.Style.STROKE); canvas.drawRect(rect, paint); // undo the translate canvas.translate(-x, -y); // rotate the canvas on center of the text to draw canvas.rotate(-45, x + rect.exactCenterX(), y + rect.exactCenterY()); // draw the rotated text paint.setStyle(Paint.Style.FILL); canvas.drawText(str2rotate, x, y, paint); //undo the translation and rotation canvas.restore(); } } } |
我要稍后尝试的其他方法是沿路径绘制文本。
另请参见此处的完整答案，该图片给出了下图。
在画布上绘制文本的另一种(可能更好)的方法是使用
1 2 3 4 5 6 7 8 9 10 | String text ="This is some text."; TextPaint textPaint = new TextPaint(); textPaint.setAntiAlias(true); textPaint.setTextSize(16 * getResources().getDisplayMetrics().density); textPaint.setColor(0xFF000000); int width = (int) textPaint.measureText(text); StaticLayout staticLayout = new StaticLayout(text, textPaint, (int) width, Layout.Alignment.ALIGN_NORMAL, 1.0f, 0, false); staticLayout.draw(canvas); |
为了便于说明，