如何创建布局？

Question

我正在尝试在我的 Android 应用程序中显示带有类似于此图片的节点的三角形

而且我只有两个可绘制对象。第一个是圆形的，第二个是直线的。 我在互联网上搜索了很多，但没有找到任何解决方案来解决我应该使用哪种布局以及如何在 Android 上实现显示这个三角形。

我无法拍摄这个三角形的完整图像，因为节点会在运行时显示一些动态数据。

Answer 1

借助 Android Canvas 及其方法 drawLines() 和 drawCircle() 使用自定义视图

这里是创建Custom Views 的方法，这里是一个非常漂亮的简短tutorial，介绍如何使用这些方法绘制任何形状。

样本

// somewhere in the constructor, call this
private void init() {
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setColor(Color.RED);
    mPaint.setStyle(Paint.Style.STROKE);
    // mPaint.setStrokeWidth(SOME_VALUE);
    ...
}

// override onSizeChanged() to make your measurements.
// if you need 'finer' control, override onMeasure(), but be careful with that one
// (read its javadocs before you override it).
// measurements include shape and text locations and sizes, etc.
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    mTriangleVertices[0] = 0.2  * w; // x0
    mTriangleVertices[1] = 0.15 * h; // y0

    mTriangleVertices[2] = 0.5  * w; // x1
    mTriangleVertices[3] = 0.85 * h; // y1

    mTriangleVertices[4] = 0.8  * w; // x2
    mTriangleVertices[5] = 0.15 * h; // y2
    // other calculations...
}

// after you save your measurements to some fields, override onDraw().
// use all the tools you created and the info you gathers above here.
// avoid creating objects at all cost. read the docs for more info.
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas); // include this first, last or you can even omit it sometimes

    canvas.drawLines(mTriangleVertices, 0, mTriangleVertices.length, mPaint);

    // canvas.drawCircle(); canvas.drawOval(); etc..
}