Java tutorial
/* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.marshalchen.common.uimodule.modifysys; import android.content.Context; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; /** * PagerTabStrip is an interactive indicator of the current, next, * and previous pages of a {@link android.support.v4.view.ViewPager}. It is intended to be used as a * child view of a ViewPager widget in your XML layout. * Add it as a child of a ViewPager in your layout file and set its * android:layout_gravity to TOP or BOTTOM to pin it to the top or bottom * of the ViewPager. The title from each page is supplied by the method * {@link android.support.v4.view.PagerAdapter#getPageTitle(int)} in the adapter supplied to * the ViewPager. * * <p>For a non-interactive indicator, see {@link android.support.v4.view.PagerTitleStrip}.</p> */ public class PagerTabStrip extends PagerTitleStrip { private static final String TAG = "PagerTabStrip"; private static final int INDICATOR_HEIGHT = 3; // dp private static final int MIN_PADDING_BOTTOM = INDICATOR_HEIGHT + 3; // dp private static final int TAB_PADDING = 16; // dp private static final int TAB_SPACING = 32; // dp private static final int MIN_TEXT_SPACING = TAB_SPACING + TAB_PADDING * 2; // dp private static final int FULL_UNDERLINE_HEIGHT = 1; // dp private static final int MIN_STRIP_HEIGHT = 32; // dp private int mIndicatorColor; private int mIndicatorHeight; private int mMinPaddingBottom; private int mMinTextSpacing; private int mMinStripHeight; private int mTabPadding; private final Paint mTabPaint = new Paint(); private final Rect mTempRect = new Rect(); private int mTabAlpha = 0xFF; private boolean mDrawFullUnderline = false; private boolean mDrawFullUnderlineSet = false; private int mFullUnderlineHeight; private boolean mIgnoreTap; private float mInitialMotionX; private float mInitialMotionY; private int mTouchSlop; public PagerTabStrip(Context context) { this(context, null); } public PagerTabStrip(Context context, AttributeSet attrs) { super(context, attrs); mIndicatorColor = mTextColor; mTabPaint.setColor(mIndicatorColor); // Note: this follows the rules for Resources#getDimensionPixelOffset/Size: // sizes round up, offsets round down. final float density = context.getResources().getDisplayMetrics().density; mIndicatorHeight = (int) (INDICATOR_HEIGHT * density + 0.5f); mMinPaddingBottom = (int) (MIN_PADDING_BOTTOM * density + 0.5f); mMinTextSpacing = (int) (MIN_TEXT_SPACING * density); mTabPadding = (int) (TAB_PADDING * density + 0.5f); mFullUnderlineHeight = (int) (FULL_UNDERLINE_HEIGHT * density + 0.5f); mMinStripHeight = (int) (MIN_STRIP_HEIGHT * density + 0.5f); mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); // Enforce restrictions setPadding(getPaddingLeft(), getPaddingTop(), getPaddingRight(), getPaddingBottom()); setTextSpacing(getTextSpacing()); setWillNotDraw(false); mPrevText.setFocusable(true); mPrevText.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mPager.setCurrentItem(mPager.getCurrentItem() - 1); } }); mNextText.setFocusable(true); mNextText.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { mPager.setCurrentItem(mPager.getCurrentItem() + 1); } }); if (getBackground() == null) { mDrawFullUnderline = true; } } /** * Set the color of the tab indicator bar. * * @param color Color to set as an 0xRRGGBB value. The high byte (alpha) is ignored. */ public void setTabIndicatorColor(int color) { mIndicatorColor = color; mTabPaint.setColor(mIndicatorColor); invalidate(); } /** * Set the color of the tab indicator bar from a color resource. * * @param resId Resource ID of a color resource to load */ public void setTabIndicatorColorResource(int resId) { setTabIndicatorColor(getContext().getResources().getColor(resId)); } /** * @return The current tab indicator color as an 0xRRGGBB value. */ public int getTabIndicatorColor() { return mIndicatorColor; } @Override public void setPadding(int left, int top, int right, int bottom) { if (bottom < mMinPaddingBottom) { bottom = mMinPaddingBottom; } super.setPadding(left, top, right, bottom); } @Override public void setTextSpacing(int textSpacing) { if (textSpacing < mMinTextSpacing) { textSpacing = mMinTextSpacing; } super.setTextSpacing(textSpacing); } @Override public void setBackgroundDrawable(Drawable d) { super.setBackgroundDrawable(d); if (!mDrawFullUnderlineSet) { mDrawFullUnderline = d == null; } } @Override public void setBackgroundColor(int color) { super.setBackgroundColor(color); if (!mDrawFullUnderlineSet) { mDrawFullUnderline = (color & 0xFF000000) == 0; } } @Override public void setBackgroundResource(int resId) { super.setBackgroundResource(resId); if (!mDrawFullUnderlineSet) { mDrawFullUnderline = resId == 0; } } /** * Set whether this tab strip should draw a full-width underline in the * current tab indicator color. * * @param drawFull true to draw a full-width underline, false otherwise */ public void setDrawFullUnderline(boolean drawFull) { mDrawFullUnderline = drawFull; mDrawFullUnderlineSet = true; invalidate(); } /** * Return whether or not this tab strip will draw a full-width underline. * This defaults to true if no background is set. * * @return true if this tab strip will draw a full-width underline in the * current tab indicator color. */ public boolean getDrawFullUnderline() { return mDrawFullUnderline; } @Override int getMinHeight() { return Math.max(super.getMinHeight(), mMinStripHeight); } @Override public boolean onTouchEvent(MotionEvent ev) { final int action = ev.getAction(); if (action != MotionEvent.ACTION_DOWN && mIgnoreTap) { return false; } // Any tap within touch slop to either side of the current item // will scroll to prev/next. final float x = ev.getX(); final float y = ev.getY(); switch (action) { case MotionEvent.ACTION_DOWN: mInitialMotionX = x; mInitialMotionY = y; mIgnoreTap = false; break; case MotionEvent.ACTION_MOVE: if (Math.abs(x - mInitialMotionX) > mTouchSlop || Math.abs(y - mInitialMotionY) > mTouchSlop) { mIgnoreTap = true; } break; case MotionEvent.ACTION_UP: if (x < mCurrText.getLeft() - mTabPadding) { mPager.setCurrentItem(mPager.getCurrentItem() - 1); } else if (x > mCurrText.getRight() + mTabPadding) { mPager.setCurrentItem(mPager.getCurrentItem() + 1); } break; } return true; } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); final int height = getHeight(); final int bottom = height; final int left = mCurrText.getLeft() - mTabPadding; final int right = mCurrText.getRight() + mTabPadding; final int top = bottom - mIndicatorHeight; mTabPaint.setColor(mTabAlpha << 24 | (mIndicatorColor & 0xFFFFFF)); canvas.drawRect(left, top, right, bottom, mTabPaint); if (mDrawFullUnderline) { mTabPaint.setColor(0xFF << 24 | (mIndicatorColor & 0xFFFFFF)); canvas.drawRect(getPaddingLeft(), height - mFullUnderlineHeight, getWidth() - getPaddingRight(), height, mTabPaint); } } @Override void updateTextPositions(int position, float positionOffset, boolean force) { final Rect r = mTempRect; int bottom = getHeight(); int left = mCurrText.getLeft() - mTabPadding; int right = mCurrText.getRight() + mTabPadding; int top = bottom - mIndicatorHeight; r.set(left, top, right, bottom); super.updateTextPositions(position, positionOffset, force); mTabAlpha = (int) (Math.abs(positionOffset - 0.5f) * 2 * 0xFF); left = mCurrText.getLeft() - mTabPadding; right = mCurrText.getRight() + mTabPadding; r.union(left, top, right, bottom); invalidate(r); } }