Java tutorial
/* * Copyright (C) 2015 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.yzx.frames.tool.view_self.percent; import android.annotation.SuppressLint; import android.content.Context; import android.content.res.TypedArray; import android.support.v4.view.MarginLayoutParamsCompat; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.Log; import android.view.View; import android.view.ViewGroup; import com.yzx.frames.R; /** * Helper for layouts that want to support percentage based dimensions. * * <p> * This class collects utility methods that are involved in extracting percentage based dimension attributes and applying them to * ViewGroup's children. If you would like to implement a layout that supports percentage based dimensions, you need to take several steps: * * <ol> * <li>You need a {@link ViewGroup.LayoutParams} subclass in your ViewGroup that implements * {@link android.support.percent.PercentLayoutHelper.PercentLayoutParams}. * <li>In your {@code LayoutParams(Context c, AttributeSet attrs)} constructor create an instance of * {@link PercentLayoutHelper.PercentLayoutInfo} by calling {@link PercentLayoutHelper#getPercentLayoutInfo(Context, AttributeSet)}. Return * this object from {@code public PercentLayoutHelper.PercentLayoutInfo getPercentLayoutInfo()} method that you implemented for * {@link android.support.percent.PercentLayoutHelper.PercentLayoutParams} interface. * <li>Override {@link ViewGroup.LayoutParams#setBaseAttributes(TypedArray, int, int)} with a single line implementation * {@code PercentLayoutHelper.fetchWidthAndHeight(this, a, widthAttr, heightAttr);} * <li>In your ViewGroup override {@link ViewGroup#generateLayoutParams(AttributeSet)} to return your LayoutParams. * <li>In your {@link ViewGroup#onMeasure(int, int)} override, you need to implement following pattern: * * <pre class="prettyprint"> * protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { * mHelper.adjustChildren(widthMeasureSpec, heightMeasureSpec); * super.onMeasure(widthMeasureSpec, heightMeasureSpec); * if (mHelper.handleMeasuredStateTooSmall()) { * super.onMeasure(widthMeasureSpec, heightMeasureSpec); * } * } * </pre> * * <li>In your {@link ViewGroup#onLayout(boolean, int, int, int, int)} override, you need to implement following pattern: * * <pre class="prettyprint"> * protected void onLayout(boolean changed, int left, int top, int right, int bottom) { * super.onLayout(changed, left, top, right, bottom); * mHelper.restoreOriginalParams(); * } * </pre> * * </ol> */ public class PercentLayoutHelper { private static final String TAG = "PercentLayout"; private final ViewGroup mHost; public PercentLayoutHelper(ViewGroup host) { mHost = host; } /** * Helper method to be called from {@link ViewGroup.LayoutParams#setBaseAttributes} override that reads layout_width and layout_height * attribute values without throwing an exception if they aren't present. */ public static void fetchWidthAndHeight(ViewGroup.LayoutParams params, TypedArray array, int widthAttr, int heightAttr) { params.width = array.getLayoutDimension(widthAttr, 0); params.height = array.getLayoutDimension(heightAttr, 0); } /** * Iterates over children and changes their width and height to one calculated from percentage values. * * @param widthMeasureSpec * Width MeasureSpec of the parent ViewGroup. * @param heightMeasureSpec * Height MeasureSpec of the parent ViewGroup. */ public void adjustChildren(int widthMeasureSpec, int heightMeasureSpec) { if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "adjustChildren: " + mHost + " widthMeasureSpec: " + View.MeasureSpec.toString(widthMeasureSpec) + " heightMeasureSpec: " + View.MeasureSpec.toString(heightMeasureSpec)); } int widthHint = View.MeasureSpec.getSize(widthMeasureSpec); int heightHint = View.MeasureSpec.getSize(heightMeasureSpec); for (int i = 0, N = mHost.getChildCount(); i < N; i++) { View view = mHost.getChildAt(i); ViewGroup.LayoutParams params = view.getLayoutParams(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "should adjust " + view + " " + params); } if (params instanceof PercentLayoutParams) { PercentLayoutInfo info = ((PercentLayoutParams) params).getPercentLayoutInfo(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "using " + info); } if (info != null) { if (params instanceof ViewGroup.MarginLayoutParams) { info.fillMarginLayoutParams((ViewGroup.MarginLayoutParams) params, widthHint, heightHint); } else { info.fillLayoutParams(params, widthHint, heightHint); } } } } } /** * Constructs a PercentLayoutInfo from attributes associated with a View. Call this method from * {@code LayoutParams(Context c, AttributeSet attrs)} constructor. */ public static PercentLayoutInfo getPercentLayoutInfo(Context context, AttributeSet attrs) { PercentLayoutInfo info = null; TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.PercentLayout_Layout); float value = array.getFraction(R.styleable.PercentLayout_Layout_layout_widthPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent width: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.widthPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_heightPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent height: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.heightPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.leftMarginPercent = value; info.topMarginPercent = value; info.rightMarginPercent = value; info.bottomMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginLeftPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent left margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.leftMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginTopPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent top margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.topMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginRightPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent right margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.rightMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginBottomPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent bottom margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.bottomMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginStartPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent start margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.startMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_marginEndPercent, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent end margin: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.endMarginPercent = value; } value = array.getFraction(R.styleable.PercentLayout_Layout_layout_aspectRatio, 1, 1, -1f); if (value != -1f) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "aspect ratio: " + value); } info = info != null ? info : new PercentLayoutInfo(); info.aspectRatio = value; } array.recycle(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "constructed: " + info); } return info; } /** * Iterates over children and restores their original dimensions that were changed for percentage values. Calling this method only makes * sense if you previously called {@link PercentLayoutHelper#adjustChildren(int, int)}. */ public void restoreOriginalParams() { for (int i = 0, N = mHost.getChildCount(); i < N; i++) { View view = mHost.getChildAt(i); ViewGroup.LayoutParams params = view.getLayoutParams(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "should restore " + view + " " + params); } if (params instanceof PercentLayoutParams) { PercentLayoutInfo info = ((PercentLayoutParams) params).getPercentLayoutInfo(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "using " + info); } if (info != null) { if (params instanceof ViewGroup.MarginLayoutParams) { info.restoreMarginLayoutParams((ViewGroup.MarginLayoutParams) params); } else { info.restoreLayoutParams(params); } } } } } /** * Iterates over children and checks if any of them would like to get more space than it received through the percentage dimension. * * If you are building a layout that supports percentage dimensions you are encouraged to take advantage of this method. The developer * should be able to specify that a child should be remeasured by adding normal dimension attribute with {@code wrap_content} value. For * example he might specify child's attributes as {@code app:layout_widthPercent="60%p"} and {@code android:layout_width="wrap_content"} * . In this case if the child receives too little space, it will be remeasured with width set to {@code WRAP_CONTENT}. * * @return True if the measure phase needs to be rerun because one of the children would like to receive more space. */ public boolean handleMeasuredStateTooSmall() { boolean needsSecondMeasure = false; for (int i = 0, N = mHost.getChildCount(); i < N; i++) { View view = mHost.getChildAt(i); ViewGroup.LayoutParams params = view.getLayoutParams(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "should handle measured state too small " + view + " " + params); } if (params instanceof PercentLayoutParams) { PercentLayoutInfo info = ((PercentLayoutParams) params).getPercentLayoutInfo(); if (info != null) { if (shouldHandleMeasuredWidthTooSmall(view, info)) { needsSecondMeasure = true; params.width = ViewGroup.LayoutParams.WRAP_CONTENT; } if (shouldHandleMeasuredHeightTooSmall(view, info)) { needsSecondMeasure = true; params.height = ViewGroup.LayoutParams.WRAP_CONTENT; } } } } if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "should trigger second measure pass: " + needsSecondMeasure); } return needsSecondMeasure; } private static boolean shouldHandleMeasuredWidthTooSmall(View view, PercentLayoutInfo info) { int state = ViewCompat.getMeasuredWidthAndState(view) & ViewCompat.MEASURED_STATE_MASK; return state == ViewCompat.MEASURED_STATE_TOO_SMALL && info.widthPercent >= 0 && info.mPreservedParams.width == ViewGroup.LayoutParams.WRAP_CONTENT; } private static boolean shouldHandleMeasuredHeightTooSmall(View view, PercentLayoutInfo info) { int state = ViewCompat.getMeasuredHeightAndState(view) & ViewCompat.MEASURED_STATE_MASK; return state == ViewCompat.MEASURED_STATE_TOO_SMALL && info.heightPercent >= 0 && info.mPreservedParams.height == ViewGroup.LayoutParams.WRAP_CONTENT; } /** * Container for information about percentage dimensions and margins. It acts as an extension for {@code LayoutParams}. */ public static class PercentLayoutInfo { public float widthPercent; public float heightPercent; public float leftMarginPercent; public float topMarginPercent; public float rightMarginPercent; public float bottomMarginPercent; public float startMarginPercent; public float endMarginPercent; public float aspectRatio; /* package */final ViewGroup.MarginLayoutParams mPreservedParams; public PercentLayoutInfo() { widthPercent = -1f; heightPercent = -1f; leftMarginPercent = -1f; topMarginPercent = -1f; rightMarginPercent = -1f; bottomMarginPercent = -1f; startMarginPercent = -1f; endMarginPercent = -1f; mPreservedParams = new ViewGroup.MarginLayoutParams(0, 0); } /** * Fills {@code ViewGroup.LayoutParams} dimensions based on percentage values. */ public void fillLayoutParams(ViewGroup.LayoutParams params, int widthHint, int heightHint) { // Preserve the original layout params, so we can restore them after the measure step. mPreservedParams.width = params.width; mPreservedParams.height = params.height; // We assume that width/height set to 0 means that value was unset. This might not // necessarily be true, as the user might explicitly set it to 0. However, we use this // information only for the aspect ratio. If the user set the aspect ratio attribute, // it means they accept or soon discover that it will be disregarded. final boolean widthNotSet = params.width == 0 && widthPercent < 0; final boolean heightNotSet = params.height == 0 && heightPercent < 0; if (widthPercent >= 0) { params.width = (int) (widthHint * widthPercent); } if (heightPercent >= 0) { params.height = (int) (heightHint * heightPercent); } if (aspectRatio >= 0) { if (widthNotSet) { params.width = (int) (params.height * aspectRatio); } if (heightNotSet) { params.height = (int) (params.width / aspectRatio); } } if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "after fillLayoutParams: (" + params.width + ", " + params.height + ")"); } } /** * Fills {@code ViewGroup.MarginLayoutParams} dimensions and margins based on percentage values. */ public void fillMarginLayoutParams(ViewGroup.MarginLayoutParams params, int widthHint, int heightHint) { fillLayoutParams(params, widthHint, heightHint); // Preserver the original margins, so we can restore them after the measure step. mPreservedParams.leftMargin = params.leftMargin; mPreservedParams.topMargin = params.topMargin; mPreservedParams.rightMargin = params.rightMargin; mPreservedParams.bottomMargin = params.bottomMargin; MarginLayoutParamsCompat.setMarginStart(mPreservedParams, MarginLayoutParamsCompat.getMarginStart(params)); MarginLayoutParamsCompat.setMarginEnd(mPreservedParams, MarginLayoutParamsCompat.getMarginEnd(params)); if (leftMarginPercent >= 0) { params.leftMargin = (int) (widthHint * leftMarginPercent); } if (topMarginPercent >= 0) { params.topMargin = (int) (heightHint * topMarginPercent); } if (rightMarginPercent >= 0) { params.rightMargin = (int) (widthHint * rightMarginPercent); } if (bottomMarginPercent >= 0) { params.bottomMargin = (int) (heightHint * bottomMarginPercent); } if (startMarginPercent >= 0) { MarginLayoutParamsCompat.setMarginStart(params, (int) (widthHint * startMarginPercent)); } if (endMarginPercent >= 0) { MarginLayoutParamsCompat.setMarginEnd(params, (int) (widthHint * endMarginPercent)); } if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "after fillMarginLayoutParams: (" + params.width + ", " + params.height + ")"); } } @SuppressLint("DefaultLocale") @Override public String toString() { return String.format( "PercentLayoutInformation width: %f height %f, margins (%f, %f, " + " %f, %f, %f, %f)", widthPercent, heightPercent, leftMarginPercent, topMarginPercent, rightMarginPercent, bottomMarginPercent, startMarginPercent, endMarginPercent); } /** * Restores original dimensions and margins after they were changed for percentage based values. Calling this method only makes * sense if you previously called {@link PercentLayoutHelper.PercentLayoutInfo#fillMarginLayoutParams}. */ public void restoreMarginLayoutParams(ViewGroup.MarginLayoutParams params) { restoreLayoutParams(params); params.leftMargin = mPreservedParams.leftMargin; params.topMargin = mPreservedParams.topMargin; params.rightMargin = mPreservedParams.rightMargin; params.bottomMargin = mPreservedParams.bottomMargin; MarginLayoutParamsCompat.setMarginStart(params, MarginLayoutParamsCompat.getMarginStart(mPreservedParams)); MarginLayoutParamsCompat.setMarginEnd(params, MarginLayoutParamsCompat.getMarginEnd(mPreservedParams)); } /** * Restores original dimensions after they were changed for percentage based values. Calling this method only makes sense if you * previously called {@link PercentLayoutHelper.PercentLayoutInfo#fillLayoutParams}. */ public void restoreLayoutParams(ViewGroup.LayoutParams params) { params.width = mPreservedParams.width; params.height = mPreservedParams.height; } } /** * If a layout wants to support percentage based dimensions and use this helper class, its {@code LayoutParams} subclass must implement * this interface. * * Your {@code LayoutParams} subclass should contain an instance of {@code PercentLayoutInfo} and the implementation of this interface * should be a simple accessor. */ public interface PercentLayoutParams { PercentLayoutInfo getPercentLayoutInfo(); } }