android - 具有渐变填充和曲线形状的 Canvas 绘图

Question

我的问题标题似乎很常见..但这与其他问题不同..我尝试了很多解决方案但仍无法获得完美的解决方案。也无法理解绘制函数。

这是我到目前为止尝试过的:

public class DrawingActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_drawing);

        ImageView img=(ImageView) findViewById(R.id.img);


        Bitmap bitmap = Bitmap.createBitmap(
                1000, // Width
                300, // Height
                Bitmap.Config.ARGB_8888 // Config
        );

        // Initialize a new Canvas instance
        Canvas canvas = new Canvas(bitmap);

        // Draw a solid color on the canvas as background
        canvas.drawColor(Color.LTGRAY);

        // Initialize a new Paint instance to draw the line
        Paint paint = new Paint();
        // Line color
        paint.setColor(Color.RED);
        paint.setStyle(Paint.Style.STROKE);
        // Line width in pixels
        paint.setStrokeWidth(8);
        paint.setAntiAlias(true);


        final RectF oval = new RectF();

        // Set a pixels value to offset the line from canvas edge
        int offset = 0;

        canvas.drawLine(
                offset, // startX
                canvas.getHeight() / 2, // startY
                300, // stopX
                canvas.getHeight() / 2, // stopY
                paint // Paint
        );


        oval.set(250, 100, 300,200);

        canvas.drawArc(oval, 90, -(float) 90, false,paint);


        oval.set(450, 300, 500,350);

        canvas.drawArc(oval, 90, -(float) 90, false,paint);

        canvas.drawLine(
                300, // startX
                canvas.getHeight() -50, // startY
                1000, // stopX
                canvas.getHeight() -50, // stopY
                paint // Paint
        );

        // Display the newly created bitmap on app interface
        img.setImageBitmap(bitmap);
    }

}

我的输出:

所以我的问题是:

1. 如果有人可以解释它的要点或示例代码，我想按照预期的输出绘制曲线。
2. 想了解绘制圆弧左、上、右、下点(我已经阅读了文档，但它只是告诉他们它们是 float 的，没有关于它的描述)。
3. 我只想用渐变颜色填充这个形状，而不是整个 Canvas 。

如有任何建议，我们将不胜感激。谢谢!

Answer 1

使用路径可以绘制贝塞尔路径。

检查我的努力如下。

 private class MyDrawView extends View {
    Paint paint;
    Path mPath;

    public MyDrawView(Context context) {
        this(context, null);

    }

    public MyDrawView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);

        mPath = new Path();
        mPath.moveTo(200, 200);
        mPath.lineTo(200, 100);
        mPath.lineTo(600, 100);
        mPath.lineTo(600, 300);
        mPath.lineTo(300, 300);
        mPath.cubicTo(250, 270, 400, 170, 200, 200);

        paint = new Paint();
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(8);
        paint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setPathEffect(new CornerPathEffect(10));
        paint.setAntiAlias(true);


    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawPath(mPath, paint);
        invalidate();
    }
}

初始化此自定义 View 并添加到您的框架布局中。喜欢，

 MyDrawView myDrawView = new MyDrawView(this);
 frmCustom.addView(myDrawView);