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。
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 List<ChangeColorIconWithTextView> mTabIndicator = new ArrayList<ChangeColorIconWithTextView>(); 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脚本之家。