Java tutorial
/* * Copyright (C) 2012 Jake Wharton * * 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.baiiu.autoloopviewpager.indicator; import android.annotation.TargetApi; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.drawable.Drawable; import android.os.Build; import android.os.Parcel; import android.os.Parcelable; import android.support.v4.view.PagerAdapter; import android.util.AttributeSet; import android.util.Log; import android.view.View; import com.baiiu.autoloopviewpager.AutoLoopViewPager; import com.baiiu.autoloopviewpager.interfaces.IRealAdapter; import com.baiiu.autoloopviewpager.R; import com.baiiu.autoloopviewpager.interfaces.IPageIndicator; /** * Draws a line for each page. The current page line is colored differently * than the unselected page lines. */ public class LinePageIndicator extends View implements IPageIndicator { private static final int INVALID_POINTER = -1; private final Paint mPaintUnselected = new Paint(Paint.ANTI_ALIAS_FLAG); private final Paint mPaintSelected = new Paint(Paint.ANTI_ALIAS_FLAG); private AutoLoopViewPager mViewPager; private int mCurrentPage; private boolean mCentered; private float mLineWidth; private float mGapWidth; private float mLastMotionX = -1; private int mActivePointerId = INVALID_POINTER; private boolean mIsDragging; public LinePageIndicator(Context context) { this(context, null); } public LinePageIndicator(Context context, AttributeSet attrs) { super(context, attrs); init(context, attrs); } public LinePageIndicator(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context, attrs); } @TargetApi(Build.VERSION_CODES.LOLLIPOP) public LinePageIndicator(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); init(context, attrs); } private void init(Context context, AttributeSet attrs) { if (isInEditMode()) return; final Resources res = getResources(); //Load defaults from resources final int defaultSelectedColor = Color.parseColor("#FF33B5E5"); final int defaultUnselectedColor = Color.parseColor("#FFBBBBBB"); final float defaultLineWidth = 36; final float defaultGapWidth = 12; final float defaultStrokeWidth = 3; final boolean defaultCentered = true; //Retrieve styles attributes TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.LinePageIndicator); mCentered = a.getBoolean(R.styleable.LinePageIndicator_centered, defaultCentered); mLineWidth = a.getDimension(R.styleable.LinePageIndicator_lineWidth, defaultLineWidth); mGapWidth = a.getDimension(R.styleable.LinePageIndicator_gapWidth, defaultGapWidth); setStrokeWidth(a.getDimension(R.styleable.LinePageIndicator_strokeWidth, defaultStrokeWidth)); mPaintUnselected .setColor(a.getColor(R.styleable.LinePageIndicator_unselectedColor, defaultUnselectedColor)); mPaintSelected.setColor(a.getColor(R.styleable.LinePageIndicator_selectedColor, defaultSelectedColor)); Drawable background = a.getDrawable(R.styleable.LinePageIndicator_android_background); if (background != null) { setBackgroundDrawable(background); } a.recycle(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec)); } /** * Determines the width of this view * * @param measureSpec A measureSpec packed into an int * @return The width of the view, honoring constraints from measureSpec */ private int measureWidth(int measureSpec) { float result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if ((specMode == MeasureSpec.EXACTLY) || (mViewPager == null)) { //We were told how big to be result = specSize; } else { //Calculate the width according the views count final int count = mViewPager.getAdapter().getCount(); result = getPaddingLeft() + getPaddingRight() + (count * mLineWidth) + ((count - 1) * mGapWidth); //Respect AT_MOST value if that was what is called for by measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return (int) Math.ceil(result); } /** * Determines the height of this view * * @param measureSpec A measureSpec packed into an int * @return The height of the view, honoring constraints from measureSpec */ private int measureHeight(int measureSpec) { float result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { //We were told how big to be result = specSize; } else { //Measure the height result = mPaintSelected.getStrokeWidth() + getPaddingTop() + getPaddingBottom(); //Respect AT_MOST value if that was what is called for by measureSpec if (specMode == MeasureSpec.AT_MOST) { result = Math.min(result, specSize); } } return (int) Math.ceil(result); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); if (mViewPager == null) { return; } final int count = getRealCount(); if (count == 0) { return; } if (mCurrentPage >= count) { setCurrentItem(count - 1); return; } final float lineWidthAndGap = mLineWidth + mGapWidth; final float indicatorWidth = (count * lineWidthAndGap) - mGapWidth; final float paddingTop = getPaddingTop(); final float paddingLeft = getPaddingLeft(); final float paddingRight = getPaddingRight(); float verticalOffset = paddingTop + ((getHeight() - paddingTop - getPaddingBottom()) / 2.0f); float horizontalOffset = paddingLeft; if (mCentered) { horizontalOffset += ((getWidth() - paddingLeft - paddingRight) / 2.0f) - (indicatorWidth / 2.0f); } //Draw stroked circles for (int i = 0; i < count; i++) { float dx1 = horizontalOffset + (i * lineWidthAndGap); float dx2 = dx1 + mLineWidth; canvas.drawLine(dx1, verticalOffset, dx2, verticalOffset, (i == mCurrentPage) ? mPaintSelected : mPaintUnselected); } } @Override public void setViewPager(AutoLoopViewPager viewPager) { if (viewPager == null || viewPager.getAdapter() == null) { throw new IllegalStateException("you must initial the viewpager with adapter"); } int initialPosition = 0; viewPager.addOnPageChangeListener(this); initialPosition = viewPager.getCurrentItem(); this.mViewPager = viewPager; setCurrentItem(initialPosition); } @Override public void setCurrentItem(int item) { onPageSelected(item); } @Override public void notifyDataSetChanged() { requestLayout(); invalidate(); } @Override public void onPageScrollStateChanged(int state) { } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { mCurrentPage = position % getRealCount(); invalidate(); } private int getRealCount() { if (mViewPager == null) { return 0; } try { PagerAdapter adapter = mViewPager.getAdapter(); if (adapter instanceof IRealAdapter) { return ((IRealAdapter) adapter).getRealCount(); } return adapter.getCount(); } catch (Exception e) { Log.e(getClass().getSimpleName(), e.toString()); return 0; } } @Override public void onRestoreInstanceState(Parcelable state) { SavedState savedState = (SavedState) state; super.onRestoreInstanceState(savedState.getSuperState()); mCurrentPage = savedState.currentPage; requestLayout(); } @Override public Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState savedState = new SavedState(superState); savedState.currentPage = mCurrentPage; return savedState; } static class SavedState extends BaseSavedState { int currentPage; public SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); currentPage = in.readInt(); } @Override public void writeToParcel(Parcel dest, int flags) { super.writeToParcel(dest, flags); dest.writeInt(currentPage); } @SuppressWarnings("UnusedDeclaration") public static final Creator<SavedState> CREATOR = new Creator<SavedState>() { @Override public SavedState createFromParcel(Parcel in) { return new SavedState(in); } @Override public SavedState[] newArray(int size) { return new SavedState[size]; } }; } public void setCentered(boolean centered) { mCentered = centered; invalidate(); } public boolean isCentered() { return mCentered; } public void setUnselectedColor(int unselectedColor) { mPaintUnselected.setColor(unselectedColor); invalidate(); } public int getUnselectedColor() { return mPaintUnselected.getColor(); } public void setSelectedColor(int selectedColor) { mPaintSelected.setColor(selectedColor); invalidate(); } public int getSelectedColor() { return mPaintSelected.getColor(); } public void setLineWidth(float lineWidth) { mLineWidth = lineWidth; invalidate(); } public float getLineWidth() { return mLineWidth; } public void setStrokeWidth(float lineHeight) { mPaintSelected.setStrokeWidth(lineHeight); mPaintUnselected.setStrokeWidth(lineHeight); invalidate(); } public float getStrokeWidth() { return mPaintSelected.getStrokeWidth(); } public void setGapWidth(float gapWidth) { mGapWidth = gapWidth; invalidate(); } public float getGapWidth() { return mGapWidth; } }