DevFest DC 2017: Cool ConstraintLayout

Huyen's talk given at DevFest DC 2017 on the cool things about and the cool things to do with ConstraintLayout.

1. HUYEN TUE DAO @QUEENCODEMONKEY COOL CONSTRAINT LAYOUT
2. COOL THINGS ABOUT CONSTRAINT LAYOUT COOL THINGS TO DO WITH CONSTRAINT LAYOUT
3. WHAT IS THE CONSTRAINT LAYOUT?
4. RELATIONSHIPS BETWEEN VIEWS RELATIVE LAYOUT++ + (≈LINEARLAYOUT) EXPRESSIVE PERFORMANT
5. UNBUNDLED SUPPORTS API 9+ UI BUILDER USABLE WITH XML ONLY
6. HOW DOES IT WORK?
7. CONSTRAINTS EQUATIONS SOLVER 7 HOW DOES IT WORK?
8. HOW DOES IT WORK? CONSTRAINTS EQUATIONS SOLVER POSITION FIXED WRAP CONTENT MATCH CONSTRAINT RATIO EDGE CENTER BASELINE DIMENSION OTHER 8 GUIDELINES CHAINS CONSTRAINT SET
9. CONSTRAINTS EQUATIONS SOLVER LINEAR SYSTEM OF EQUATIONS/INEQUALITIES 9 HOW DOES IT WORK? 11 + … + 1n = 11 + … + 1n ≤ 11 + … + 1n ≥
10. CONSTRAINTS EQUATIONS SOLVER CASSOWARY LINEAR ARITHMETIC CONSTRAINT SOLVING ALGORITHM VIEW BOUNDS 10 HOW DOES IT WORK?
11. CONSTRAINTLAYOUT, INSIDE AND OUT: PART 2 DAVE SMITH
12. LET’S TAKE A QUICK TOUR
14. CONSTRAINT LAYOUT CHEAT SHEET
15. SOURCE TARGET EDGE CONSTRAINT 
 app:layout_constraintLeft_toLeftOf="parent" 
 app:layout_constraint<source>_to<target>Of=“a_view"
16. CENTER CONSTRAINT 
 app:layout_constraintHorizontal_bias="0.75"
17. BASELINE CONSTRAINT app:layout_constraintBaseline_toBaselineOf="@+id/view"
18. SIZE CONSTRAINTS
19. GUIDELINES
20. <android.support.constraint.Guideline
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:id="@+id/guideline_start"
 android:orientation="vertical"
 app:layout_constraintGuide_begin="16dp" />
 
 
 <android.support.constraint.Guideline
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:id="@+id/horizontal"
 android:orientation="horizontal"
 app:layout_constraintGuide_percent="0.37" />
21. SO WHAT CAN WE DO WITH CONSTRAINT LAYOUT?
22. public class SquareImageView extends ImageView { @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 
 final int size = Math.min(getMeasuredWidth(), getMeasuredHeight());
 setMeasuredDimension(size, size);
 }
23. <ImageView
 android:id=“@+id/square_image”
 android:layout_width="0dp"
 android:layout_height="0dp"
 app:layout_constraintDimensionRatio=“W,1:1"
25. <!-- Dimension ratios -->
 <string name="dimension_ratio_home_hero">H,16:10</string> <!-- In action in XML --> app:layout_constraintDimensionRatio=“@string/hero_ratio"
26. IS IT REALLY BETTER THAN RELATIVE LAYOUT?
27. STYLING ANDROID CONSTRAINTLAYOUT PART 6
29. private fun updateManualAnchors() {
 val size = anchorMinSize + seekBar.progress
 val halfSize = Math.round(size * 0.5f)
 val horizontalMargin = resources.getDimensionPixelSize(R.dimen.content_margin_horizontal) - halfSize
 val verticalMargin = resources.getDimensionPixelSize(R.dimen.alignment_rectangle_margin_vertical) - halfSize
 updateManualAnchor(frameAnchorTop, size, verticalMargin, 0, 0, 0)
 updateManualAnchor(frameAnchorStart, size, 0, horizontalMargin, 0, 0)
 updateManualAnchor(frameAnchorBottom, size, 0, 0, verticalMargin, 0)
 updateManualAnchor(frameAnchorEnd, size, 0, 0, 0, horizontalMargin)
 }
 
 private fun updateManualAnchor(anchor: View, size: Int,
 marginTop: Int, marginStart: Int,
 marginBottom: Int, marginEnd: Int) {
 val layoutParams = anchor.layoutParams as FrameLayout.LayoutParams layoutParams.width = size
 layoutParams.height = size
 layoutParams.topMargin = marginTop
 layoutParams.bottomMargin = marginBottom
 layoutParams.marginStart = marginStart
 layoutParams.marginEnd = marginEnd anchor.layoutParams = layoutParams
 } WITH CONSTRAINTLAYOUT JUST CHANGE THE SIZE…
30. WHAT WAS THAT ABOUT LINEAR LAYOUT?
31. CHAINS. CHAINS. CHAINS. FROM CONSTRAINTLAYOUT DOCUMENTATION
32. SPREAD INSIDE CHAIN <TextView
 android:id=“@+id/spread_inside_head”
 app:layout_constraintHorizontal_chainStyle="spread_inside"
 … />
33. <TextView
 android:id=“@+id/weighted_chain_head
 android:layout_width="0dp"
 android:layout_height="wrap_content"
 app:layout_constraintHorizontal_chainStyle="spread"
 app:layout_constraintHorizontal_weight=“1" /> <TextView
 android:id=“@+id/next android:layout_width="0dp"
 android:layout_height="wrap_content"
 app:layout_constraintHorizontal_weight="2" /> <TextView
 android:id=“@+id/last
 android:layout_width="0dp"
 android:layout_height="wrap_content"
 app:layout_constraintHorizontal_weight="1" /> 33 WEIGHTED CHAIN
34. <TextView
 android:id=“@+id/packed_chain_head”
 app:layout_constraintHorizontal_chainStyle="packed"
 app:layout_constraintHorizontal_bias="0.12" /> 34 PACKED CHAIN
36. A CONSTRAINT LAYOUT SPECIAL CONSTRAINT SET
37. CONSTRAINT SET CREATE/SAVE/APPLY CREATE MANUALLY CLONE A LAYOUT FILE CLONE A CONSTRAINT LAYOUT AWESOME WITH TRANSITIONS DEFINE SET OF CONSTRAINTS PROGRAMMATICALLY
39. // Inflate initial layout as usual. setContentView(R.layout.activity_constraintset_01) // Get references to controls
 constraintLayout = findViewById(R.id.constraint_layout) as ConstraintLayout
 
 // Load ConstraintSets.
 constraintSet01.clone(constraintLayout)
 constraintSet02.clone(this, R.layout.activity_constraintset_02) …some time later… // Toggle ConstraintSets. TransitionManager.beginDelayedTransition(constraintLayout)
 if (original) constraintSet02.applyTo(constraintLayout)
 else constraintSet01.applyTo(constraintLayout)
 original = !original 39
40. YES, LIST ITEMS CAN BE CONSTRAINT LAYOUTS
41. CONSTRAINT SET IN LIEU OF CUSTOM VIEWGROUP
42. CUSTOM VIEW GROUPS GENERALIZED, REUSABLE LAYOUTS PERFORMANT COMPOSITE LAYOUTS LAYOUT IS LOW-LEVEL (X, Y) EVEN SIMPLE ONES = MUCH CODE ADVANCED LAYOUTS… WOAH
43. @Override
 protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
 MarginLayoutParams layoutParams = (MarginLayoutParams) icon.getLayoutParams();
 
 // Figure out the x-coordinate and y-coordinate of the icon.
 int x = getPaddingLeft() + layoutParams.leftMargin;
 int y = getPaddingTop() + layoutParams.topMargin;
 
 // Layout the icon.
 icon.layout(x, y, x + icon.getMeasuredWidth(), y + icon.getMeasuredHeight());
 
 // Calculate the x-coordinate of the title: icon's right coordinate +
 // the icon's right margin.
 x += icon.getMeasuredWidth() + layoutParams.rightMargin;
 
 // Add in the title's left margin.
 layoutParams = (MarginLayoutParams) titleView.getLayoutParams();
 x += layoutParams.leftMargin;
 
 // Calculate the y-coordinate of the title: this ViewGroup's top padding +
 // the title's top margin
 y = getPaddingTop() + layoutParams.topMargin;
 
 // Layout the title.
 titleView.layout(x, y, x + titleView.getMeasuredWidth(), y + titleView.getMeasuredHeight());
 
 // The subtitle has the same x-coordinate as the title. So no more calculating there.
 
 // Calculate the y-coordinate of the subtitle: the title's bottom coordinate +
 // the title's bottom margin.
 y += titleView.getMeasuredHeight() + layoutParams.bottomMargin;
 layoutParams = (MarginLayoutParams) subtitleView.getLayoutParams();
 
 // Add in the subtitle's top margin.
 y += layoutParams.topMargin;
 
 // Layout the subtitle.
 subtitleView.layout(x, y,
 x + subtitleView.getMeasuredWidth(), y + subtitleView.getMeasuredHeight());
 } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // Measure icon. measureChildWithMargins(icon, widthMeasureSpec, 0, heightMeasureSpec, 0); // Figure out how much width the icon used. MarginLayoutParams lp = (MarginLayoutParams) icon.getLayoutParams(); int widthUsed = icon.getMeasuredWidth() + lp.leftMargin + lp.rightMargin; int heightUsed = 0; // Measure title measureChildWithMargins( titleView, // Pass width constraints and width already used. widthMeasureSpec, widthUsed, // Pass height constraints and height already used. heightMeasureSpec, heightUsed ); // Measure the Subtitle. measureChildWithMargins( subtitleView, // Pass width constraints and width already used. widthMeasureSpec, widthUsed, // Pass height constraints and height already used. heightMeasureSpec, titleView.getMeasuredHeight()); // Calculate this view's measured width and height. // Figure out how much total space the icon used. int iconWidth = icon.getMeasuredWidth() + lp.leftMargin + lp.rightMargin; int iconHeight = icon.getMeasuredHeight() + lp.topMargin + lp.bottomMargin; lp = (MarginLayoutParams) titleView.getLayoutParams(); // Figure out how much total space the title used. int titleWidth = titleView.getMeasuredWidth() + lp.leftMargin + lp.rightMargin; int titleHeight = titleView.getMeasuredHeight() + lp.topMargin + lp.bottomMargin; lp = (MarginLayoutParams) subtitleView.getLayoutParams(); // Figure out how much total space the subtitle used. int subtitleWidth = subtitleView.getMeasuredWidth() + lp.leftMargin + lp.rightMargin; int subtitleHeight = subtitleView.getMeasuredHeight() + lp.topMargin + lp.bottomMargin; // The width taken by the children + padding. int width = getPaddingTop() + getPaddingBottom() + iconWidth + Math.max(titleWidth, subtitleWidth); // The height taken by the children + padding. int height = getPaddingTop() + getPaddingBottom() + Math.max(iconHeight, titleHeight + subtitleHeight); // Reconcile the measured dimensions with the this view's constraints and // set the final measured width and height. setMeasuredDimension( resolveSize(width, widthMeasureSpec), resolveSize(height, heightMeasureSpec) ); }
44. CONSTRAINT SET IN LIEU OF CUSTOM VIEWGROUP
45. private fun addRow(view: View) {
 constraintLayout.addView(view)
 
 val id = view.id
 constraintSet.constrainWidth(id, MATCH_CONSTRAINT)
 constraintSet.constrainHeight(id, rowHeight)
 
 // Constrain new view vertically.
 val target = if (lastRowId  PARENT_ID) TOP else BOTTOM
 constraintSet.connect(id, TOP, lastRowId, target) // Constrain new view horizontally.
 constraintSet.connect(id, START, PARENT_ID, START)
 constraintSet.connect(id, END, PARENT_ID, END)
 
 // Toggle elevation to elevate last added view.
 constraintSet.setElevation(id, resources.getDimension(R.dimen.elevation))
 constraintSet.setElevation(lastViewId, 0f)
 
 // Apply constraints.
 constraintSet.applyTo(constraintLayout) 45
46. private fun addRowItem(view: View) {
 …
 constraintLayout.addView(view)
 
 val id = view.id
 
 // Initialize width and height of new view.
 constraintSet.constrainWidth(id, MATCH_CONSTRAINT)
 constraintSet.constrainHeight(id, rowHeight)
 
 // Constrain new view vertically.
 val target = if (lastRowId  PARENT_ID) TOP else BOTTOM
 constraintSet.connect(id, TOP, lastRowId, target) 46
47. // Update current row.
 currentRowIds.add(id)
 // Re-create horizontal chain with other row items.
 constraintSet.createHorizontalChainRtl(
 PARENT_ID, START,
 PARENT_ID, END,
 currentRowIds.toIntArray(), FloatArray(currentRow.size, { 1f }),
 CHAIN_SPREAD_INSIDE)
 
 // Toggle elevation to elevate last added view.
 constraintSet.setElevation(id, resources.getDimension(R.dimen.elevation))
 constraintSet.setElevation(lastViewId, 0f)
 
 // Apply constraints.
 constraintSet.applyTo(constraintLayout) 47
48. SERIOUSLY COOL THINGS IN CONSTRAINT LAYOUT
49. ANDROID DEVELOPERS BACKSTAGE EPISODE 50: CONSTRAINT LAYOUT
50. CONSTRAINTLAYOUT CREW JOHN HOFORD @JOHNHOFORD NICOLAS ROARD @CAMAELON
51. THANK YOU! SPEAKERDECK.COM/QUEENCODEMONKEY YOUTUBE.COM/ANDROIDDIALOGS RANDOMLYTYPING.COM HUYEN TUE DAO @QUEENCODEMONKEY QUEENCODEMONKEY/PRESENTATION-COOL-CONSTRAINTLAYOUT
52. REFERENCES 52 CONSTRAINT LAYOUT APIS DOCUMENTATION https://developer.android.com/reference/android/support/constraint/package-summary.html BUILD A RESPONSIVE UI WITH CONSTRAINTLAYOUT developer.android.com/training/constraint-layout/index.html ANDROID DEVELOPERS BACKSTAGE: EPISODE 50: CONSTRAINT LAYOUT androidbackstage.blogspot.com/2016/06/episode-50-constraint-layout.html USING CONSTRAINTLAYOUT TO DESIGN YOUR VIEWS | CODE LABS codelabs.developers.google.com/codelabs/constraint-layout/index.html ANDROID LAYOUTS: A NEW WORLD | GOOGLE I/O 2016 https://youtu.be/sO9aX87hq9c CONSTRAINTLAYOUT https://speakerdeck.com/writtmeyer/constraintlayout-1 ADVANCED CONSTRAINTLAYOUT http://cfp.devoxx.us/2017/talk/XOD-8930/Advanced_ConstraintLayout
53. REFERENCES 53 CONSTRAINTLAYOUT – PART 1 blog.stylingandroid.com/constraintlayout-part-1/ CONSTRAINTLAYOUT, INSIDE AND OUT: PART 1 http://wiresareobsolete.com/2016/07/constraintlayout-part-1/ SOME THOUGHTS ON ANDROID’S NEW CONSTRAINTLAYOUT AND ANDROID STUDIO’S NEW DESIGN EDITOR http://www.grokkingandroid.com/thoughts-on-constraintlayout-and-design-editor/ BUILD A UI WITH LAYOUT EDITOR developer.android.com/studio/write/layout-editor.html WHAT'S NEW IN ANDROID DEVELOPMENT TOOLS | GOOGLE I/O 2016 https://youtu.be/csaXml4xtN8 THE EXPERTS' GUIDE TO ANDROID DEVELOPMENT TOOLS | GOOGLE I/O 2016 https://youtu.be/hHnTIMjd1Y8 JOHN HOFORD & NICOLAS ROARD : CONSTRAINTLAYOUT | ANDROID DIALOGS https://youtu.be/hHnTIMjd1Y8