自定义view实现一个游标效果

本文主要是介绍自定义view实现一个游标效果，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

最近公司的项目中需要一个游标效果控件，可以滑动游标选择相应的时间域。设计效果图如下：

于是乎，决定自己动手实现一下这个效果，也算是复习自定义view相关知识。

首先，自定义属性：attr.xml

    <declare-styleable name="CursorView"><attr name="current_bg_color" format="color|reference"></attr><attr name="current_text_color" format="color|reference"></attr><attr name="incurrent_text_color" format="color|reference"></attr><attr name="textsize" format="dimension"></attr><attr name="stroke_width" format="dimension"></attr><attr name="stroke_color" format="color|reference"></attr></declare-styleable>

自定义View类如下：

package com.baicells.omcserver.view;import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.TypedArray;
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.support.annotation.Nullable;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewParent;import com.baicells.omcserver.R;import java.util.ArrayList;public class CursorView extends View {private int width;private int height;private int radius;private int strokeWidth;private int curTextColor;private int inCurTextColor;private ArrayList<String> cursorText;private Paint borderPaint;private Paint innerBgPaint;private Paint textPaint;private int current;private float offsetX;private RectF currentRectF;private boolean isInCurrent;public CursorView(Context context) {super(context);}public CursorView(Context context, @Nullable AttributeSet attrs) {super(context, attrs);borderPaint = new Paint();borderPaint.setAntiAlias(true);borderPaint.setStyle(Paint.Style.FILL.STROKE);innerBgPaint = new Paint();innerBgPaint.setAntiAlias(true);innerBgPaint.setStyle(Paint.Style.FILL_AND_STROKE);textPaint = new Paint();textPaint.setAntiAlias(true);TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CursorView);int indexCount = typedArray.getIndexCount();for (int i = 0; i < indexCount; i++) {int index = typedArray.getIndex(i);switch (index) {case R.styleable.CursorView_current_bg_color:innerBgPaint.setColor(typedArray.getColor(index, Color.GREEN));break;case R.styleable.CursorView_current_text_color:curTextColor = typedArray.getColor(index, Color.WHITE);break;case R.styleable.CursorView_incurrent_text_color:inCurTextColor = typedArray.getColor(index, Color.BLACK);break;case R.styleable.CursorView_stroke_color:borderPaint.setColor(typedArray.getColor(index, Color.RED));break;case R.styleable.CursorView_textsize:textPaint.setTextSize(typedArray.getDimensionPixelSize(index, 20));break;case R.styleable.CursorView_stroke_width:strokeWidth = typedArray.getDimensionPixelSize(index, 3);break;}}typedArray.recycle();borderPaint.setStrokeWidth(strokeWidth);setLayerType(LAYER_TYPE_SOFTWARE, null);}public CursorView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}public void setCursorText(ArrayList<String> cursorText) {this.cursorText = cursorText;invalidate();}public void setCurrent(int current) {this.current = current;invalidate();}public int getCurrent() {return current;}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);int modeWidth = MeasureSpec.getMode(widthMeasureSpec);int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);int modeHeight = MeasureSpec.getMode(heightMeasureSpec);width = 300;height = 20;if (modeWidth == MeasureSpec.EXACTLY) {width = sizeWidth;}if (modeHeight == MeasureSpec.EXACTLY) {height = sizeHeight;}setMeasuredDimension(width, height);radius = height / 2;}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);//画整个大背景RectF rect = new RectF(strokeWidth / 2, strokeWidth / 2, width - strokeWidth / 2, height - strokeWidth / 2);canvas.drawRoundRect(rect, radius, radius, borderPaint);if (cursorText != null) {int size = cursorText.size();float everyWidth = width * 1.0f / size;//画当前选中时间维度的背景RectF currBgRectF = getCurrBgRectF(everyWidth);currentRectF = currBgRectF;canvas.drawRoundRect(currBgRectF, radius, radius, innerBgPaint);//循环画时间维度文本for (int i = 0; i < size; i++) {textPaint.setShader(null);String text = cursorText.get(i);Paint.FontMetricsInt metricsInt = textPaint.getFontMetricsInt();float textwidth = textPaint.measureText(text);float preblank = (everyWidth - textwidth) / 2.0f;float x = everyWidth * i + preblank;float y = (height - metricsInt.bottom + metricsInt.top) / 2.0f - metricsInt.top;if (currBgRectF.left >= x && currBgRectF.left <= x + textwidth) {float split = (currBgRectF.left - x) / textwidth;LinearGradient shader = new LinearGradient(x, 0, x + textwidth,0, new int[]{inCurTextColor, curTextColor}, new float[]{split, split + 0.01f}, Shader.TileMode.CLAMP);textPaint.setShader(shader);}if (currBgRectF.right >= x && currBgRectF.right <= x + textwidth) {float split = (currBgRectF.right - x) / textwidth;LinearGradient shader = new LinearGradient(x, 0, x + textwidth,0, new int[]{curTextColor, inCurTextColor}, new float[]{split, split + 0.01f}, Shader.TileMode.CLAMP);textPaint.setShader(shader);}if (currBgRectF.left < x && currBgRectF.right > x + textwidth) {textPaint.setColor(curTextColor);} else {textPaint.setColor(inCurTextColor);}canvas.drawText(text, x, y, textPaint);}}}private RectF getCurrBgRectF(float everyWidth) {float left = everyWidth * current + offsetX;float right = everyWidth * (current + 1) + offsetX;if (left < 0) {left = 0;right = everyWidth;}if (right > width) {left = width - everyWidth;right = width;}return new RectF(left, 0, right, height);}@Overridepublic boolean dispatchTouchEvent(MotionEvent ev) {ViewParent parent = null;while (true) {if (parent != null && parent instanceof ViewPager) {break;}if (parent != null) {parent = parent.getParent();} else {parent = getParent();}}switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:case MotionEvent.ACTION_MOVE:case MotionEvent.ACTION_UP:parent.requestDisallowInterceptTouchEvent(true);break;default:parent.requestDisallowInterceptTouchEvent(false);break;}return super.dispatchTouchEvent(ev);}private float downX = 0;private float downY = 0;@Overridepublic boolean onTouchEvent(MotionEvent event) {float x = event.getX();switch (event.getAction()) {case MotionEvent.ACTION_DOWN:downX = event.getX();downY = event.getY();isInCurrent = currentRectF.contains(downX, downY);break;case MotionEvent.ACTION_MOVE:if (isInCurrent) {offsetX = x - downX;invalidate();}break;case MotionEvent.ACTION_UP:if (isInCurrent) {final NextCurrent nextCurrent = computeScrollX(currentRectF.left);final float lastX = offsetX;ValueAnimator anim = ValueAnimator.ofFloat(0, nextCurrent.getX());anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator animation) {float value = (float) animation.getAnimatedValue();offsetX = lastX + value;invalidate();float fraction = animation.getAnimatedFraction();if (fraction == 1.0f) {current = nextCurrent.getIndex();offsetX = 0;invalidate();}}});anim.setDuration(100);anim.start();}break;}return true;}private NextCurrent computeScrollX(float left) {NextCurrent next = new NextCurrent();int index = 0;if (cursorText != null) {int size = cursorText.size();float everyWidth = width * 1.0f / size;float min = everyWidth + 1;for (int i = 0; i < size; i++) {float abs = Math.abs(left - everyWidth * i);if (abs < min) {min = abs;index = i;}}if (everyWidth * index > left) {next.setX(min);} else {next.setX(-min);}next.setIndex(index);}return next;}private class NextCurrent {private int index;private float x;public int getIndex() {return index;}public void setIndex(int index) {this.index = index;}public float getX() {return x;}public void setX(float x) {this.x = x;}}
}

本控件支持的特性：

1、上述自定义View代码涉及到了手势滑动相关处理，当前选中的时间域背景跟随手指滑动进行移动，当手指抬起时，计算当前位置，并选择最近的时间域进行回弹（类似ViewPager中page页回弹效果）。

2、手指拖动当前时间域进行滑动过程中，对于不同时间域的文本内容，当内容与时间域背景有重叠时，支持颜色变化。

3、由于我的项目中自定义View是用在ViewPager下，所以有处理滑动冲突，当手指触摸位置为自定义View时请求父View不拦截事件，由当前自定义View处理该事件。

当前page页面对应的xml布局文件中的代码部分：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"><com.baicells.omcserver.view.CursorViewandroid:id="@+id/cursor"android:layout_width="328dp"android:layout_height="28dp"android:layout_gravity="center_horizontal"android:layout_marginTop="16dp"app:current_bg_color="@android:color/holo_green_light"app:current_text_color="@android:color/white"app:incurrent_text_color="@android:color/black"app:stroke_color="@android:color/holo_green_light"app:stroke_width="2dp"app:textsize="14sp" /></LinearLayout>

运行效果截图：