1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.example.android.apis.view; 18 19 // Need the following import to get access to the app resources, since this 20 // class is in a sub-package. 21 import android.graphics.Rect; 22 import com.example.android.apis.R; 23 24 //BEGIN_INCLUDE(Complete) 25 import android.content.Context; 26 import android.content.res.TypedArray; 27 import android.util.AttributeSet; 28 import android.view.Gravity; 29 import android.view.View; 30 import android.view.ViewGroup; 31 import android.widget.RemoteViews; 32 33 /** 34 * Example of writing a custom layout manager. This is a fairly full-featured 35 * layout manager that is relatively general, handling all layout cases. You 36 * can simplify it for more specific cases. 37 */ 38 @RemoteViews.RemoteView 39 public class CustomLayout extends ViewGroup { 40 /** The amount of space used by children in the left gutter. */ 41 private int mLeftWidth; 42 43 /** The amount of space used by children in the right gutter. */ 44 private int mRightWidth; 45 46 /** These are used for computing child frames based on their gravity. */ 47 private final Rect mTmpContainerRect = new Rect(); 48 private final Rect mTmpChildRect = new Rect(); 49 50 public CustomLayout(Context context) { 51 super(context); 52 } 53 54 public CustomLayout(Context context, AttributeSet attrs) { 55 this(context, attrs, 0); 56 } 57 58 public CustomLayout(Context context, AttributeSet attrs, int defStyle) { 59 super(context, attrs, defStyle); 60 } 61 62 /** 63 * Any layout manager that doesn't scroll will want this. 64 */ 65 @Override 66 public boolean shouldDelayChildPressedState() { 67 return false; 68 } 69 70 /** 71 * Ask all children to measure themselves and compute the measurement of this 72 * layout based on the children. 73 */ 74 @Override 75 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 76 int count = getChildCount(); 77 78 // These keep track of the space we are using on the left and right for 79 // views positioned there; we need member variables so we can also use 80 // these for layout later. 81 mLeftWidth = 0; 82 mRightWidth = 0; 83 84 // Measurement will ultimately be computing these values. 85 int maxHeight = 0; 86 int maxWidth = 0; 87 int childState = 0; 88 89 // Iterate through all children, measuring them and computing our dimensions 90 // from their size. 91 for (int i = 0; i < count; i++) { 92 final View child = getChildAt(i); 93 if (child.getVisibility() != GONE) { 94 // Measure the child. 95 measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0); 96 97 // Update our size information based on the layout params. Children 98 // that asked to be positioned on the left or right go in those gutters. 99 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 100 if (lp.position == LayoutParams.POSITION_LEFT) { 101 mLeftWidth += Math.max(maxWidth, 102 child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin); 103 } else if (lp.position == LayoutParams.POSITION_RIGHT) { 104 mRightWidth += Math.max(maxWidth, 105 child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin); 106 } else { 107 maxWidth = Math.max(maxWidth, 108 child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin); 109 } 110 maxHeight = Math.max(maxHeight, 111 child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin); 112 childState = combineMeasuredStates(childState, child.getMeasuredState()); 113 } 114 } 115 116 // Total width is the maximum width of all inner children plus the gutters. 117 maxWidth += mLeftWidth + mRightWidth; 118 119 // Check against our minimum height and width 120 maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight()); 121 maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth()); 122 123 // Report our final dimensions. 124 setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState), 125 resolveSizeAndState(maxHeight, heightMeasureSpec, 126 childState << MEASURED_HEIGHT_STATE_SHIFT)); 127 } 128 129 /** 130 * Position all children within this layout. 131 */ 132 @Override 133 protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 134 final int count = getChildCount(); 135 136 // These are the far left and right edges in which we are performing layout. 137 int leftPos = getPaddingLeft(); 138 int rightPos = right - left - getPaddingRight(); 139 140 // This is the middle region inside of the gutter. 141 final int middleLeft = leftPos + mLeftWidth; 142 final int middleRight = rightPos - mRightWidth; 143 144 // These are the top and bottom edges in which we are performing layout. 145 final int parentTop = getPaddingTop(); 146 final int parentBottom = bottom - top - getPaddingBottom(); 147 148 for (int i = 0; i < count; i++) { 149 final View child = getChildAt(i); 150 if (child.getVisibility() != GONE) { 151 final LayoutParams lp = (LayoutParams) child.getLayoutParams(); 152 153 final int width = child.getMeasuredWidth(); 154 final int height = child.getMeasuredHeight(); 155 156 // Compute the frame in which we are placing this child. 157 if (lp.position == LayoutParams.POSITION_LEFT) { 158 mTmpContainerRect.left = leftPos + lp.leftMargin; 159 mTmpContainerRect.right = leftPos + width + lp.rightMargin; 160 leftPos = mTmpContainerRect.right; 161 } else if (lp.position == LayoutParams.POSITION_RIGHT) { 162 mTmpContainerRect.right = rightPos - lp.rightMargin; 163 mTmpContainerRect.left = rightPos - width - lp.leftMargin; 164 rightPos = mTmpContainerRect.left; 165 } else { 166 mTmpContainerRect.left = middleLeft + lp.leftMargin; 167 mTmpContainerRect.right = middleRight - lp.rightMargin; 168 } 169 mTmpContainerRect.top = parentTop + lp.topMargin; 170 mTmpContainerRect.bottom = parentBottom - lp.bottomMargin; 171 172 // Use the child's gravity and size to determine its final 173 // frame within its container. 174 Gravity.apply(lp.gravity, width, height, mTmpContainerRect, mTmpChildRect); 175 176 // Place the child. 177 child.layout(mTmpChildRect.left, mTmpChildRect.top, 178 mTmpChildRect.right, mTmpChildRect.bottom); 179 } 180 } 181 } 182 183 // ---------------------------------------------------------------------- 184 // The rest of the implementation is for custom per-child layout parameters. 185 // If you do not need these (for example you are writing a layout manager 186 // that does fixed positioning of its children), you can drop all of this. 187 188 @Override 189 public LayoutParams generateLayoutParams(AttributeSet attrs) { 190 return new CustomLayout.LayoutParams(getContext(), attrs); 191 } 192 193 @Override 194 protected LayoutParams generateDefaultLayoutParams() { 195 return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT); 196 } 197 198 @Override 199 protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) { 200 return new LayoutParams(p); 201 } 202 203 @Override 204 protected boolean checkLayoutParams(ViewGroup.LayoutParams p) { 205 return p instanceof LayoutParams; 206 } 207 208 /** 209 * Custom per-child layout information. 210 */ 211 public static class LayoutParams extends MarginLayoutParams { 212 /** 213 * The gravity to apply with the View to which these layout parameters 214 * are associated. 215 */ 216 public int gravity = Gravity.TOP | Gravity.START; 217 218 public static int POSITION_MIDDLE = 0; 219 public static int POSITION_LEFT = 1; 220 public static int POSITION_RIGHT = 2; 221 222 public int position = POSITION_MIDDLE; 223 224 public LayoutParams(Context c, AttributeSet attrs) { 225 super(c, attrs); 226 227 // Pull the layout param values from the layout XML during 228 // inflation. This is not needed if you don't care about 229 // changing the layout behavior in XML. 230 TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.CustomLayoutLP); 231 gravity = a.getInt(R.styleable.CustomLayoutLP_android_layout_gravity, gravity); 232 position = a.getInt(R.styleable.CustomLayoutLP_layout_position, position); 233 a.recycle(); 234 } 235 236 public LayoutParams(int width, int height) { 237 super(width, height); 238 } 239 240 public LayoutParams(ViewGroup.LayoutParams source) { 241 super(source); 242 } 243 } 244 } 245 //END_INCLUDE(Complete) 246
