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Android仿微信底部按钮滑动变色，这里只针对使用Fragment为Tab页的滑动操作，进行简单的变色讲解。
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首先说下OnPageChangeListener这个监听
//这个监听有三个方法 public abstract void onPageScrollStateChanged (int state) public abstract void onPageScrolled (int position, float positionOffset, int positionOffsetPixels) public abstract void onPageSelected (int position) //第一个方法onPageScrollStateChanged 中的参数state，有三个可取的值 public static final int SCROLL_STATE_DRAGGING Constant Value: 1 (0x00000001) //手指按在ViewPager上滑动时 public static final int SCROLL_STATE_IDLE Constant Value: 0 (0x00000000) //手指松开后，ViewPager自动滑动期间 public static final int SCROLL_STATE_SETTLING Constant Value: 2 (0x00000002) //ViewPager进入了某个Page //如果在onPageScrollStateChanged 中输出state的值，你会发现每次都是按顺序打印出“1---2---0” //第二个方法onPageScrolled的三个参数 position：//滑动时，屏幕左侧显示的第一个page positionOffset：//滑动比例，值的范围为[0, 1)，手指往左滑动，该值递增，反之递减 positionOffsetPixels：//滑动距离，和屏幕有关，手指往左滑动，该值递增，反之递减 //我们经常需要检查viewpager的滑动方向并作出一些操作，这时你只需要通过position和positionOffset两个值即可实现该功能。 //比如实现微信底部图标颜色渐变 向左滑动时 ChangeColorIconWithTextView left = mTabIndicator.get(position); //左侧显示的第一个page页面上底部图标和文字的初始化 ChangeColorIconWithTextView right = mTabIndicator.get(position + 1); //右侧显示的Page底部图标和文字的初始化 left.setIconAlpha(1 - positionOffset); //设置图标的透明度 此时positionOffset值递增 左侧图标的颜色变浅 right.setIconAlpha(positionOffset); //右侧图标的颜色逐渐变深 //第三个方法onPageSelected的三个参数 position：//当前选择的page序号 //该方法被调用的时间比较特别，在上面的第一个方法中的“1---2----0”中的2执行之后，onPageSelected就执行，然后执行“1---2----0”中的0。就是手指松开屏幕之后，onPageSelected被执行。
上面提到了ChangeColorIconWithTextView 主要类
package com.mhealth.nursestation.app.pda.business.login.base.ui.fragmentutil;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Looper;
import android.os.Parcelable;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;
import com.mhealth.nursestation.app.pda.R;
/**
* 此类用于修改颜色渐变
*/
public class ChangeColorIconWithTextView extends View {
private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mPaint;
/**
* 颜色
*/
private int mColor = 0XFF07B7C4;
/**
* 透明度 0.0-1.0 初始化必须是0 不是0就废了
*/
private float mAlpha = 0f;
/**
* 图标
*/
private Bitmap mIconBitmap;
/**
* 限制绘制icon的范围
*/
private Rect mIconRect;
/**
* icon底部文本
*/
private String mText = "微信";
private int mTextSize = (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 10, getResources().getDisplayMetrics());
private Paint mTextPaint;
private Rect mTextBound = new Rect();
public ChangeColorIconWithTextView(Context context) {
super(context);
}
/**
* 初始化自定义属性值
*
* @param context
* @param attrs
*/
public ChangeColorIconWithTextView(Context context, AttributeSet attrs) {
super(context, attrs);
// 获取设置的图标
TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.ChangeColorIconView);
int n = a.getIndexCount();
for (int i = 0; i < n; i++) {
int attr = a.getIndex(i);
switch (attr) {
case R.styleable.ChangeColorIconView_icon:
BitmapDrawable drawable = (BitmapDrawable) a.getDrawable(attr);
mIconBitmap = drawable.getBitmap();
break;
case R.styleable.ChangeColorIconView_color:
mColor = a.getColor(attr, 0x07B7C4);
break;
case R.styleable.ChangeColorIconView_text:
mText = a.getString(attr);
break;
case R.styleable.ChangeColorIconView_text_size:
mTextSize = (int) a.getDimension(attr, TypedValue
.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10,
getResources().getDisplayMetrics()));
break;
}
}
a.recycle();
mTextPaint = new Paint();
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(0xff07B7C4);
mTextPaint.setAntiAlias(true);
// 得到text绘制范围
mTextPaint.getTextBounds(mText, 0, mText.length(), mTextBound);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// 得到绘制icon的宽
int bitmapWidth = Math.min(getMeasuredWidth() - getPaddingLeft()
- getPaddingRight(), getMeasuredHeight() - getPaddingTop()
- getPaddingBottom() - mTextBound.height());
int left = getMeasuredWidth() / 2 - bitmapWidth / 2;
int top = (getMeasuredHeight() - mTextBound.height()) / 2 - bitmapWidth
/ 2;
// 得到绘制icon的宽
mIconRect = new Rect(left, top, left + bitmapWidth, top + bitmapWidth);
}
@Override
protected void onDraw(Canvas canvas) {
int alpha = (int) Math.ceil((255 * mAlpha));
canvas.drawBitmap(mIconBitmap, null, mIconRect, null);
setupTargetBitmap(alpha);
drawSourceText(canvas, alpha);
drawTargetText(canvas, alpha);
canvas.drawBitmap(mBitmap, 0, 0, null);
}
private void setupTargetBitmap(int alpha) {
mBitmap = Bitmap.createBitmap(getMeasuredWidth(), getMeasuredHeight(),
Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mPaint = new Paint();
mPaint.setColor(mColor);
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setAlpha(alpha);
mCanvas.drawRect(mIconRect, mPaint);
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
mPaint.setAlpha(255);
mCanvas.drawBitmap(mIconBitmap, null, mIconRect, mPaint);
}
/**
* 透明度 255
*
* @param canvas
* @param alpha
*/
private void drawSourceText(Canvas canvas, int alpha) {
mTextPaint.setTextSize(mTextSize);
mTextPaint.setColor(0x00333333);
mTextPaint.setAlpha(255 - alpha);
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
- mTextBound.width() / 2,
mIconRect.bottom + mTextBound.height(), mTextPaint);
}
private void drawTargetText(Canvas canvas, int alpha) {
mTextPaint.setColor(mColor);
mTextPaint.setAlpha(alpha);
canvas.drawText(mText, mIconRect.left + mIconRect.width() / 2
- mTextBound.width() / 2,
mIconRect.bottom + mTextBound.height(), mTextPaint);
}
public void setIconAlpha(float alpha) {
this.mAlpha = alpha;
invalidateView();
}
private void invalidateView() {
if (Looper.getMainLooper() == Looper.myLooper()) {
invalidate();
} else {
postInvalidate();
}
}
public void setIconColor(int color) {
mColor = color;
}
public void setIcon(int resId) {
this.mIconBitmap = BitmapFactory.decodeResource(getResources(), resId);
if (mIconRect != null)
invalidateView();
}
public void setIcon(Bitmap iconBitmap) {
this.mIconBitmap = iconBitmap;
if (mIconRect != null)
invalidateView();
}
private static final String INSTANCE_STATE = "instance_state";
private static final String STATE_ALPHA = "state_alpha";
@Override
protected Parcelable onSaveInstanceState() {
Bundle bundle = new Bundle();
bundle.putParcelable(INSTANCE_STATE, super.onSaveInstanceState());
bundle.putFloat(STATE_ALPHA, mAlpha);
return bundle;
}
@Override
protected void onRestoreInstanceState(Parcelable state) {
if (state instanceof Bundle) {
Bundle bundle = (Bundle) state;
mAlpha = bundle.getFloat(STATE_ALPHA);
super.onRestoreInstanceState(bundle.getParcelable(INSTANCE_STATE));
} else {
super.onRestoreInstanceState(state);
}
}
}
在Activity里面实现监听操作
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (positionOffset > 0) {
ChangeColorIconWithTextView left = mTabIndicator.get(position);
ChangeColorIconWithTextView right = mTabIndicator.get(position + 1);
left.setIconAlpha(1 - positionOffset);
right.setIconAlpha(positionOffset);
}
}
定义一个集合，将所有变色控件装载进去
private ListmTabIndicator = new ArrayList (); private void initTabIndicator() { ChangeColorIconWithTextView one = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_one); ChangeColorIconWithTextView two = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_two); ChangeColorIconWithTextView three = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_three); ChangeColorIconWithTextView four = (ChangeColorIconWithTextView) findViewById(R.id.id_indicator_four); mTabIndicator.add(one); mTabIndicator.add(two); mTabIndicator.add(three); mTabIndicator.add(four); one.setOnClickListener(this); two.setOnClickListener(this); three.setOnClickListener(this); four.setOnClickListener(this); one.setIconAlpha(1.0f); }
点击监听
@Override
public void onClick(View v) {
resetOtherTabs();
switch (v.getId()) {
case R.id.id_indicator_one:
mTabIndicator.get(0).setIconAlpha(1.0f);
mViewPager.setCurrentItem(0, false);
break;
case R.id.id_indicator_two:
mTabIndicator.get(1).setIconAlpha(1.0f);
mViewPager.setCurrentItem(1, false);
break;
case R.id.id_indicator_three:
mTabIndicator.get(2).setIconAlpha(1.0f);
mViewPager.setCurrentItem(2, false);
mAppContext.has_new_talk = false;
break;
case R.id.id_indicator_four:
mTabIndicator.get(3).setIconAlpha(1.0f);
mViewPager.setCurrentItem(3, false);
break;
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持创新互联。