/*
* 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 android.support.percent;
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 android.support.percent.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;
}
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;
/* 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;
if (widthPercent >= 0) {
params.width = (int) (widthHint * widthPercent);
}
if (heightPercent >= 0) {
params.height = (int) (heightHint * heightPercent);
}
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
+ ")");
}
}
@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();
}
}