如何在Android中创建半圆形图像视图

Question

我想创建一个半圆/圆形图像视图.下面是我用来创建圆形图像视图的代码,但我无法创建半圆形图像(半圆)

package com.example.dynamicviews;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.widget.ImageView;

/**
 * Customized Imageview with Rounded Border and Shadow
 * @author Rahul Gupta <rahulg@exzeo.com>
 * @since 2014-01-01
 */
public class RoundedImageView extends ImageView
{
    private int borderWidth = 2;
    private int viewWidth;
    private int viewHeight;
    private Bitmap image;
    private Paint paint;
    private Paint paintBorder;
    private BitmapShader shader;

    public RoundedImageView(Context context)
    {
        super(context);
        setup();
    }

    public RoundedImageView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        setup();
    }

    public RoundedImageView(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        setup();
    }

    /**
     * Custom Class to round imageview with color
     * @param context Context of the activity
     * @param borderColor Border color to be set
     */
    @SuppressLint("NewApi")
    public RoundedImageView(Context context, String borderColor) {
        super(context);
         // init paint
        paint = new Paint();
        paint.setAntiAlias(true);
        paintBorder = new Paint();
        setBorderColor(Color.WHITE);
        paintBorder.setAntiAlias(true);
        this.setLayerType(LAYER_TYPE_SOFTWARE, paintBorder);
        paintBorder.setShadowLayer(3.0f, 0.0f,1.0f, Color.parseColor(borderColor));
    }

    @SuppressLint("NewApi")
    private void setup()
    {
        // init paint
        paint = new Paint();
        paint.setAntiAlias(true);
        paintBorder = new Paint();
        setBorderColor(Color.WHITE);
        paintBorder.setAntiAlias(true);
        this.setLayerType(LAYER_TYPE_SOFTWARE, paintBorder);
        paintBorder.setShadowLayer(3.0f, 0.0f,1.0f, Color.BLACK);
        loadBitmap();
    }

    public void setBorderWidth(int borderWidth)
    {
        this.borderWidth = borderWidth;
        this.invalidate();
    }

    public void setBorderColor(int borderColor)
    {
        if (paintBorder != null)
            paintBorder.setColor(borderColor);

        this.invalidate();
    }

    private void loadBitmap()
    {
        BitmapDrawable bitmapDrawable = (BitmapDrawable) this.getDrawable();

        if (bitmapDrawable != null)
            image = bitmapDrawable.getBitmap();
    }

    @SuppressLint("DrawAllocation")
    @Override
    public void onDraw(Canvas canvas)
    {
        // load the bitmap

        // init shader
        if (image != null)
        {
            shader = new BitmapShader(Bitmap.createScaledBitmap(image, canvas.getWidth(), canvas.getHeight(), false), Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            paint.setShader(shader);
            int circleCenter = viewWidth / 2;

            // circleCenter is the x or y of the view's center
            // radius is the radius in pixels of the cirle to be drawn
            // paint contains the shader that will texture the shape
            canvas.drawCircle(circleCenter + borderWidth, circleCenter + borderWidth, circleCenter + borderWidth - 4.0f, paintBorder);
            canvas.drawCircle(circleCenter + borderWidth, circleCenter + borderWidth, circleCenter - 4.0f, paint);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        int width = measureWidth(widthMeasureSpec);
        int height = measureHeight(heightMeasureSpec, widthMeasureSpec);

        viewWidth = width - (borderWidth * 2);
        viewHeight = height - (borderWidth * 2);

        setMeasuredDimension(width, height);
    }

    private int measureWidth(int measureSpec)
    {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY)
        {
            // We were told how big to be
            result = specSize;
        }
        else
        {
            // Measure the text
            result = viewWidth;
        }

        return result;
    }

    private int measureHeight(int measureSpecHeight, int measureSpecWidth)
    {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpecHeight);
        int specSize = MeasureSpec.getSize(measureSpecHeight);

        if (specMode == MeasureSpec.EXACTLY)
        {
            // We were told how big to be
            result = specSize;
        }
        else
        {
            // Measure the text (beware: ascent is a negative number)
            result = viewHeight;
        }

        return (result + 2);
    }
}

这是它的截图: -

所需的结果如下所示: - 两个imageview的左半圆和右半圆,其间有图像资源: -

Answer 1

我的一个项目我有相同的半圆，里面需要显示一些图像，所以我只使用简单的技巧，我只创建一个半圆图像并设置为图像视图的src，然后我设置另一张图像作为背景。您还可以使用一些技巧，例如创建简单的框架布局并设置一些半圆形图像作为背景，并在该框架布局旁边使用一些图像视图并将其他一些图像设置为该图像视图。我希望这能给您一些完成任务的基本想法。祝你好运 ：）