扫描旋转的view

最新推荐文章于 2024-07-05 03:37:25 发布

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最新推荐文章于 2024-07-05 03:37:25 发布

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分类专栏：自定义view

本文链接：https://blog.youkuaiyun.com/baidu_28027209/article/details/79719681

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本文介绍了一个自定义Android视图ScanView的实现细节，该视图使用SweepGradient和DashPathEffect来创建动态扫描效果。文章深入探讨了如何通过Canvas API进行路径绘制、旋转动画以及颜色渐变等操作。

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这里写图片描述

import android.content.Context;
import android.graphics.*;
import android.graphics.LinearGradient;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;

public class ScanView extends View {
private final Paint mPaint;
private final Path path;
private final int n = 6;
private final float R = 250;
private final float R0 = 240;
private final float R1 = 300;
private final Path path1;
private final Handler handler;
private SweepGradient sweepGradient;
private SweepGradient sweepGradient1;
private DashPathEffect dashPathEffect;
private int rotate = 0;
private Path path0;
private DashPathEffect dashPathEffect1;
private android.graphics.LinearGradient linearGradient;

public ScanView(Context context) {
    this(context, null);
}


public ScanView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
}


public ScanView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    mPaint = new Paint();
    setLayerType(LAYER_TYPE_SOFTWARE, mPaint);
    path = new Path();
    path1 = new Path();
    path0 = new Path();
    handler = new Handler() {
        /**
         * Subclasses must implement this to receive messages.
         *
         * @param msg
         */
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            removeCallbacksAndMessages(null);
            invalidate();
        }
    };


}


@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if (sweepGradient == null) {
        sweepGradient = new SweepGradient(0, 0, Color.WHITE, Color.parseColor("#FF5B50F2"));
        sweepGradient1 = new SweepGradient(0, 0, Color.WHITE, Color.parseColor("#FF5B50F2"));
        float degree = 360 / n;
        for (int i = 0; i < 6; i++) {
            if (i == 0) {
                path0.moveTo((float) (Math.sin(Math.toRadians(degree) * i) * R0), (float) Math.cos(Math.toRadians(degree) * i) * R0);
                path.moveTo((float) (Math.sin(Math.toRadians(degree) * i) * R), (float) Math.cos(Math.toRadians(degree) * i) * R);
                path1.moveTo((float) (Math.sin(Math.toRadians(degree) * i) * R1), (float) Math.cos(Math.toRadians(degree) * i) * R1);
            } else {
                path0.lineTo((float) (Math.sin(Math.toRadians(degree) * i) * R0), (float) Math.cos(Math.toRadians(degree) * i) * R0);
                path.lineTo((float) (Math.sin(Math.toRadians(degree) * i) * R), (float) Math.cos(Math.toRadians(degree) * i) * R);
                path1.lineTo((float) (Math.sin(Math.toRadians(degree) * i) * R1), (float) Math.cos(Math.toRadians(degree) * i) * R1);
            }
        }
        dashPathEffect = new DashPathEffect(new float[]{R, R / 2}, 0);
        dashPathEffect1 = new DashPathEffect(new float[]{R1, R1 / 2}, 0);
        linearGradient = new LinearGradient(
                getMeasuredWidth() / 2,
                0,
                getMeasuredWidth() / 2,
                getMeasuredHeight(),
                Color.parseColor("#FF5B50F2"),
                Color.parseColor("#FFFFFFFF"), Shader.TileMode.CLAMP);
        path.close();
        path1.close();
    }

    mPaint.setShader(linearGradient);
    mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    canvas.drawColor(Color.parseColor("#FFFFFFFF"));
    canvas.translate(getMeasuredWidth() / 2, getMeasuredHeight() / 2);
    canvas.drawCircle(0, 0, 400, mPaint);

// canvas.save();
if (rotate >= 360) {
rotate = 0;
}
canvas.rotate(rotate, 0, 0);
rotate = rotate + 360 / n;
drawPath1(canvas);
drawPath(canvas);
// canvas.restore();
drawPath0(canvas);
// drawInnerShape(canvas);
handler.sendEmptyMessageDelayed(0, 200);

}

private void drawPath1(Canvas canvas) {
    mPaint.setStrokeWidth(10);
    mPaint.setAntiAlias(true);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setColor(Color.WHITE);
    mPaint.setShader(sweepGradient1);
    mPaint.setPathEffect(dashPathEffect1);
    canvas.drawPath(path1, mPaint);
}

private void drawPath(Canvas canvas) {
    mPaint.setStrokeWidth(10);
    mPaint.setAntiAlias(true);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setColor(Color.WHITE);
    mPaint.setShader(null);
    mPaint.setPathEffect(dashPathEffect);
    canvas.drawPath(path, mPaint);
}

private void drawPath0(Canvas canvas) {
    mPaint.setStrokeWidth(10);
    mPaint.setAntiAlias(true);
    mPaint.setStyle(Paint.Style.FILL);
    mPaint.setColor(Color.parseColor("#FF547DF6"));
    mPaint.setPathEffect(null);
    mPaint.setShader(null);
    canvas.drawPath(path0, mPaint);
}

}