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.gosuncn.core.percentlayout; import java.util.regex.Matcher; import java.util.regex.Pattern; 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.util.TypedValue; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import com.gosuncn.core.R; /** * Helper for layouts that want to support percentage based dimensions. * <p/> * <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: * <p/> * <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 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); Log.d(TAG, "widthHint = " + widthHint + " , heightHint = " + heightHint); 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) { // textsize percent support if (view instanceof TextView) { PercentLayoutInfo.PercentVal textSizePercent = info.textSizePercent; if (textSizePercent != null) { int base = textSizePercent.isBaseWidth ? widthHint : heightHint; float textSize = (int) (base * textSizePercent.percent); ((TextView) view).setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize); } } 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); String sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_widthPercent); PercentLayoutInfo.PercentVal percentVal = getPercentVal(sizeStr, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent width: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.widthPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_heightPercent, // 1, 1, -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_heightPercent); percentVal = getPercentVal(sizeStr, false); if (sizeStr != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent height: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.heightPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginPercent, // 1, 1, -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginPercent); // just for judge percentVal = getPercentVal(sizeStr, false); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.leftMarginPercent = getPercentVal(sizeStr, true); info.topMarginPercent = getPercentVal(sizeStr, false); info.rightMarginPercent = getPercentVal(sizeStr, true); info.bottomMarginPercent = getPercentVal(sizeStr, false); } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginLeftPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginLeftPercent); percentVal = getPercentVal(sizeStr, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent left margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.leftMarginPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginTopPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginTopPercent); percentVal = getPercentVal(sizeStr, false); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent top margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.topMarginPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginRightPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginRightPercent); percentVal = getPercentVal(sizeStr, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent right margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.rightMarginPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginBottomPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginBottomPercent); percentVal = getPercentVal(sizeStr, false); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent bottom margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.bottomMarginPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginStartPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginStartPercent); percentVal = getPercentVal(sizeStr, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent start margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.startMarginPercent = percentVal; } // value = // array.getFraction(R.styleable.PercentLayout_Layout_layout_marginEndPercent, // 1, 1, // -1f); sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_marginEndPercent); percentVal = getPercentVal(sizeStr, true); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent end margin: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.endMarginPercent = percentVal; } // textSizePercent sizeStr = array.getString(R.styleable.PercentLayout_Layout_layout_textSizePercent); percentVal = getPercentVal(sizeStr, false); if (percentVal != null) { if (Log.isLoggable(TAG, Log.VERBOSE)) { Log.v(TAG, "percent text size: " + percentVal.percent); } info = info != null ? info : new PercentLayoutInfo(); info.textSizePercent = percentVal; } array.recycle(); if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "constructed: " + info); } return info; } private static final String REGEX_PERCENT = "^(([0-9]+)([.]([0-9]+))?|([.]([0-9]+))?)%([wh]?)$"; /** * widthStr to PercentVal <br/> * eg: 35%w => new PercentVal(35, true) * * @param percentStr * @param isOnWidth * @return */ private static PercentLayoutInfo.PercentVal getPercentVal(String percentStr, boolean isOnWidth) { // valid param if (percentStr == null) { return null; } Pattern p = Pattern.compile(REGEX_PERCENT); Matcher matcher = p.matcher(percentStr); if (!matcher.matches()) { throw new RuntimeException("the value of layout_xxxPercent invalid! ==>" + percentStr); } int len = percentStr.length(); // extract the float value String floatVal = matcher.group(1); String lastAlpha = percentStr.substring(len - 1); float percent = Float.parseFloat(floatVal) / 100f; boolean isBasedWidth = (isOnWidth && !lastAlpha.equals("h")) || lastAlpha.equals("w"); return new PercentLayoutInfo.PercentVal(percent, isBasedWidth); } /** * 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. * <p/> * 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.percent >= 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.percent >= 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 static class PercentVal { public float percent = -1; public boolean isBaseWidth; public PercentVal() { } public PercentVal(float percent, boolean isBaseWidth) { this.percent = percent; this.isBaseWidth = isBaseWidth; } } public PercentVal widthPercent; public PercentVal heightPercent; public PercentVal leftMarginPercent; public PercentVal topMarginPercent; public PercentVal rightMarginPercent; public PercentVal bottomMarginPercent; public PercentVal startMarginPercent; public PercentVal endMarginPercent; public PercentVal textSizePercent; /* package */final ViewGroup.MarginLayoutParams mPreservedParams; public PercentLayoutInfo() { 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; /* * if (widthPercent >= 0) { params.width = (int) (widthHint * * widthPercent); } if (heightPercent >= 0) { params.height = (int) * (heightHint * heightPercent); } */ if (widthPercent != null) { int base = widthPercent.isBaseWidth ? widthHint : heightHint; params.width = (int) (base * widthPercent.percent); } if (heightPercent != null) { int base = heightPercent.isBaseWidth ? widthHint : heightHint; params.height = (int) (base * heightPercent.percent); } 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 != null) { int base = leftMarginPercent.isBaseWidth ? widthHint : heightHint; params.leftMargin = (int) (base * leftMarginPercent.percent); } if (topMarginPercent != null) { int base = topMarginPercent.isBaseWidth ? widthHint : heightHint; params.topMargin = (int) (base * topMarginPercent.percent); } if (rightMarginPercent != null) { int base = rightMarginPercent.isBaseWidth ? widthHint : heightHint; params.rightMargin = (int) (base * rightMarginPercent.percent); } if (bottomMarginPercent != null) { int base = bottomMarginPercent.isBaseWidth ? widthHint : heightHint; params.bottomMargin = (int) (base * bottomMarginPercent.percent); } if (startMarginPercent != null) { int base = startMarginPercent.isBaseWidth ? widthHint : heightHint; MarginLayoutParamsCompat.setMarginStart(params, (int) (base * startMarginPercent.percent)); } if (endMarginPercent != null) { int base = endMarginPercent.isBaseWidth ? widthHint : heightHint; MarginLayoutParamsCompat.setMarginEnd(params, (int) (base * endMarginPercent.percent)); } if (Log.isLoggable(TAG, Log.DEBUG)) { Log.d(TAG, "after fillMarginLayoutParams: (" + params.width + ", " + params.height + ")"); } } @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 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 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. * <p/> * 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(); } }