android 自定义view实现彩虹进度条功能

目录

• 相关知识
• 实现步骤
• 自定义view
• 实现几个重构方法
• 绘制背景条
• 绘制进度图片
• 公共方法
• 总结

实现一个彩虹色进度条功能，不说明具体用途大家应该能猜到。想找别人造的轮子，但是没有合适的，所以决定自己实现一个。

相关知识

android 自定义view

LinearGradient 线性渐变

实现步骤

自定义view

自定义一个TmcView类继承View

重写两个构造方法。构造方法一共有4个，这里边重写两个

重写ongSizeChanged方法，用来获取控件宽、高，来计算内部组件尺寸。

重写onDraw方法，里边要描画背景drawBackground，分段数据drawSection，和seekbar图片drawImage。

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.Nullable;
import Java.util.List;
public class TmcView extends View {
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBackground(canvas);
        drawSection(canvas);
        drawImage(canvas);
    }
    /**
     * 画背景
     * @param canvas 画布
     */
    private void drawBackground(Canvas canvas) {
    }
    /**
     * 画分段数据
     * @param canvas 画布
     */
    private void drawSection(Canvas canvas) {
    }
    /**
     * 画图片
     * @param canvas 画布
     */
    private void drawImage(Canvas canvas) {
    }
    /**
     * 更新view
     * @param total 总长度
     * @param rest 剩余长度
     * @param sections 分段数据
     */
    public void updateView(int total, int rest, List<SectionData> sections){
    }

实现几个重构方法

标注：

整体宽度为图片宽度44px

背景条宽度30px，外边距7px，圆角15px

带颜色的条宽度20xp，外边距5px，圆角15px

自定义view的坐标轴是以view的左上角位置为原点，向右为x轴正方向，向下为y轴正方向

在视图中用RectF创建背景，和颜色条，并在onSizeChanged中设置尺寸

public class TmcView extends View {
    private final RectF backgroundRectF = new RectF();
    private final RectF colorRectF = new RectF();
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //设置矩形 left top right bottom 左上右下点的值  按照标注计算得出
        backgroundRectF.set(7, 0, 37, h);
        colorRectF.set(12, 5, 32, h-5);
    }
    ...
}

绘制背景条

实现drawBackground方法，画背景需要一根画笔Paint 为了避免重复创建，声明为成员变量

public class TmcView extends View {
    /*背景画笔*/
    private final Paint backPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final RectF backgroundRectF = new RectF();
    private final RectF colorRectF = new RectFandroid();
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //设置矩形 left top right bottom 左上右下点的值  按照标注计算得出
        backgroundRectF.set(7, 0, 37, h);
        colorRectF.set(12, 5, 32, h-5);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBackground(canvas);
        drawSection(canvas);
        drawImage(canvas);
    }
    /**
     * 画背景
     * @param canvas 画布
     */
    private void drawBackground(Canvas canvas) {
        backPaint.setStyle(Paint.Style.FILL);
        backPaint.setAntiAlias(true); //抗锯齿
        backPaint.setColor(Color.parseColor("#FFFFFF"));
        //画圆角矩形，15为圆角的角度
        canvas.drawRoundRect(backgroundRectF, 15, 15, backPaint);
    }
...
}

  布局中加入TmcView

<com.bigxuan.tesapp.view.TmcView
        android:id="@+id/tmc"
        android:layout_width="44px"
        android:layout_height="690px"
        android:layout_marginEnd="1230px"
        android:layout_marginBottom="100px"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        />

绘制颜色条

实现drawSection方法，这里要用到线性渐变LinearGradient

LinearGradient 简单说，指定每一段的颜色和位置百分比，就能实现每一段显示不同颜色。

但它默认是渐变色，要想不变就在每一段的开始和结束位置都设置相同的颜色。

再创建一个画笔 Paint，画颜色条

public class TmcView extends View {
    private final Paint backPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final Paint colorPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final RectF backgroundRectF = new RectF();
    private final RectF colorRectF = new RectF();
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //设置矩形 left top right bottom 左上右下点的值  按照标注计算得出
        backgroundRectF.set(7, 0, 37, h);
        colorRectF.set(12, 5, 32, h-5);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBackground(canvas);
        drawSection(canvas);
        drawImage(canvas);
    }
    /**
     * 画背景
     * @param canvas 画布
     */
    private void drawBackground(Canvas canvas) {
        backPaint.setStyle(Paint.Style.FILL);
        backPaint.setAntiAlias(true); //抗锯齿
        backPaint.setColor(Color.parseColor("#FFFFFF"));
        //画圆角矩形，15为圆角的角度
        canvas.drawRoundRect(backgroundRectF, 15, 15, backPaint);
    }
    /**
   js  * 画分段数据
     * @param canvas 画布
     */
    private void drawSection(Canvas canvas) {
        int[] colorArray = {
                Color.parseColor("#FF0000"), Color.parseColor("#FF0000"),
                Color.parseColor("#00FF00"), Color.parseColor("#00FF00"),
                Color.parseColor("#0000FF"), Color.parseColor("#0000FF")
        };
        float[] positionArray = {
                0f, 0.2f,
                0.2f, 0.6f,
                0.6f, 1f
        };
        colorPaint.setStyle(Paint.Style.FILL);
        colorPaint.setAntiAlias(true);
        //指定渐变色方向x轴方向不变，沿y方向渐变，渐变范围为 颜色条高度
        colorPaint.setShader(new LinearGradient(0, 0, 0, colorRectF.bottom, colorArray, positionArray, Shader.TileMode.REPEAT));
        canvas.drawRoundRect(colorRectF,15, 15, colorPaint);
    }
    ...
}

绘制进度图片

app加入图片资源，根据资源id获取bitmap对象，绘制。

需要注意的是，坐标轴的顶点在左上角，绘制图片时也是以图片左上顶点位置做定位，图片位置是view的高度减掉图片的高度，才能显示在正确位置。

public class TmcView extends View {
    private Context context;
    private final Paint backPaint = new Paint(Paint.ANTI_AxeJfjNLIAS_FLAG);
    private final Paint colorPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final RectF backgroundRectF = new RectF();
    private final RectF colorRectF = new RectF();
    /*图片资源id*/
    private int imgResId;
    /*图片位置*/
    private int imgPos;
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        this.imgResId = R.drawable.icon_seekbar_day;
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //设置矩形 left top right bottom 左上右下点的值  按照标注计算得出
        backgroundRectF.set(7, 0, 37, h);
        colorRectF.set(12, 5, 32, h-5);
        imgPos = h - 44; // 设置一个初始位置
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBackground(canvas);
        drawSection(canvas);
        drawImage(canvas);
    }
    /**
     * 画背景
     * @param canvas 画布
     */
    private void drawBackground(Canvas canvas) {
        backPaint.setStyle(Paint.Style.FILL);
        backPaint.setAntiAlias(true); //抗锯齿
        backPaint.setColor(Color.parseColor("#FFFFFF"));
        //画圆角矩形，15为圆角的角度
        canvas.drawRoundRect(backgroundRectF, 15, 15, backPaint);
    }
    /**
     * 画分段数据
     * @param canvas 画布
     */
    private void drawSection(Canvas canvas) {
        int[] colorArray = {
                Color.parseColor("#FF0000"), Color.parseColor("#FF0000"),
                Color.parseColor("#00FF00"), Color.parseColor("#00FF00"),
                Color.parseColor("#0000FF"), Color.parseColor("#0000FF")
        };
        float[] positionArray = {
                0f, 0.2f,
                0.2f, 0.6f,
                0.6f, 1f
        };
        colorPaint.setStyle(Paint.Style.FILL);
        colorPaint.setAntiAlias(true);
        //指定渐变色方向x轴方向不变，沿y方向渐变，渐变范围为 颜色条高度
        colorPaint.setShader(new LinearGradient(0, 0, 0, colorRectF.bottom, colorArray, positionArray, Shader.TileMode.REPEAT));
        canvas.drawRoundRect(colorRectF,15, 15, colorPaint);
    }
    /**
     * 画图片
     * @param canvas 画布
     */
    private void drawImage(Canvas canvas) {
        Bitmap bitmap = initBitmap(imgResId);
        canvas.save();
        canvas.translate(0, 0);
        canvas.drawBitmap(bitmap, 0, imgPos, null);
        canvas.restore();
    }
    /**
     * 通过资源id 创建bitmap
     * @param resId 资源id
     * @return
     */
    private Bitmap initBitmap(int resId) {
        Bitmap originalBmp = BitmapFactory.decodeResource(context.getResources(), resId);
        return Bitmap.createScaledBitmap(originalBmp, 44, 44, true);
    }
...
}

公共方法

暴露方法用来更新进度updateView

定义一个图片有效的运动距离为view高度减掉图片高度，函数参数为总距离和剩余距离，计算百分比后乘以有效运动距离得出图片描画位置。最后调用invalidate方法刷新view

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.view.View;
import androidx.annotation.Nullable;
import com.navinfo.tesapp.R;
import java.util.List;
public class TmcView extends View {
    private Context context;
    private final Paint backPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final Paint colorPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final RectF backgroundRectF = new RectF();
    private final RectF colorRectF = new RectF();
    /*图片资源id*/
    private int imgResId;
    /*图片位置*/
    private int imgPos;
    /*图片有效的运动距离*/
    private int imgValidHeight;
    public TmcView(Context context) {
        super(context);
    }
    public TmcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        this.imgResId = R.drawable.icon_seekbar_day;
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        //设置矩形 left top right bottom 左上右下点的值  按照标注计算得出
        backgroundRectF.set(7, 0, 37, h);
        colorRectF.set(12, 5, 32, h-5);
    android    imgValidHeight = h - 44;
        imgPos = h - 44; // 设置一个初始位置
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawBackground(canvas);
        drawSection(canvas);
        drawImage(canvas);
    }
    /**
     * 画背景
     * @param canva编程客栈s 画布
     */
    private void drawBackground(Canvas canvas) {
        backPaint.setStyle(Paint.Style.FILL);
        backPaint.setAntiAlias(true); //抗锯齿
        backPaint.setColor(Color.parseColor("#FFFFFF"));
        //画圆角矩形，15为圆角的角度
        canvas.drawRoundRect(backgroundRectF, 15, 15, backPaint);
    }
    /**
     * 画分段数据
     * @param canvas 画布
     */
    private void drawSection(Canvas canvas) {
        int[] colorArray = {
                Color.parseColor("#FF0000"), Color.parseColor("#FF0000"),
                Color.parseColor("#00FF00"), Color.parseColor("#00FF00"),
                Color.parseColor("#0000FF"), Color.parseColor("#0000FF")
        };
        float[] positionArray = {
                0f, 0.2f,
                0.2f, 0.6f,
                0.6f, 1f
        };
        colorPaint.setStyle(Paint.Style.FILL);
        colorPaint.setAntiAlias(true);
        //指定渐变色方向x轴方向不变，沿y方向渐变，渐变范围为 颜色条高度
        colorPaint.setShader(new LinearGradient(0, 0, 0, colorRectF.bottom, colorArray, positionArray, Shader.TileMode.REPEAT));
        canvas.drawRoundRect(colorRectF,15, 15, colorPaint);
    }
    /**
     * 画图片
     * @param canvas 画布
     */
    private void drawImage(Canvas canvas) {
        Bitmap bitmap = initBitmap(imgResId);
        canvas.save();
        canvas.translate(0, 0);
        canvas.drawBitmap(bitmap, 0, imgPos, null);
        canvas.restore();
    }
    /**
     *
     * @param resId
     * @return
     */
    private Bitmap initBitmap(int resId) {
        Bitmap originalBmp = BitmapFactory.decodeResource(context.getResources(), resId);
        return Bitmap.createScaledBitmap(originalBmp, 44, 44, true);
    }
    /**
     * 更新view
     * @param total 总长度
     * @param rest 剩余长度
     * @param sections 分段数据
     */
    public void updateView(int total, int rest, List<SectionData> sections){
        float percent = (1f * rest) / total;
        //防止溢出
        if(percent < 0){
            return;
        }
        imgPos = (int)(percent * imgValidHeight);
        invalidate();
    }
}

updateView方法还有第三个参数，是用来传出颜色条不同段的颜色和百分比数据的。根据此数据来更新颜色条。这里需要根据业务不同自己实现，我这里就不写了。

总结

        大家可能看出来了，这个视图是用来展示导航中不同路段交通情况和当前车辆进度用的。自定义view中可以在构造方法中获取一些自定义属性，像背景条和颜色条的边距、圆角这些都可以定义到XML中，因为只适配一种屏幕尺寸所以也没有做多尺寸适配。以前也没有做过，这次记录下来。