Dynamically Adjust Screen Item Size According To Item Count

chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm

Index: chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm
diff --git a/chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm b/chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm
index 5a660e5ae02eb48254335505ca4a96028680c17b..614b0eb82925e95bcf0ff5954f788f0b75fa467c 100644
--- a/chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm
+++ b/chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm
@@ -40,6 +40,8 @@ const CGFloat kThumbnailWidth = 150;
 const CGFloat kThumbnailHeight = 150;
 const CGFloat kSingleScreenWidth = 300;
 const CGFloat kSingleScreenHeight = 300;
+const CGFloat kMultipleScreenWidth = 220;
+const CGFloat kMultipleScreenHeight = 220;
 const CGFloat kFramePadding = 20;
 const CGFloat kControlSpacing = 10;
 const CGFloat kExcessButtonPadding = 6;
@@ -279,9 +281,12 @@ NSString* const kTitleId = @"title";
 
 - (void)createSourceViewsAtOrigin:(NSPoint)origin {
   if (screenList_) {
-    screenBrowser_.reset([[self
-        createImageBrowserWithSize:NSMakeSize(kSingleScreenWidth,
-                                              kSingleScreenHeight)] retain]);
+    const bool is_single = screenList_->GetSourceCount() <= 1;
+    const CGFloat width = is_single ? kSingleScreenWidth : kMultipleScreenWidth;
+    const CGFloat height =
+        is_single ? kSingleScreenHeight : kMultipleScreenHeight;
+    screenBrowser_.reset(
+        [[self createImageBrowserWithSize:NSMakeSize(width, height)] retain]);
   }
 
   if (windowList_) {
@@ -601,7 +606,17 @@ NSString* const kTitleId = @"title";
   // For screen source, if there is only one source, we can omit the label
   // "Entire Screen", because it is redundant with tab label "Your Entire
   // Screen".
-  [item setTitleHidden:browser == screenBrowser_ && [items count] == 1];
+  if (browser == screenBrowser_) {
+    if ([items count] > 1) {
+      [item setTitleHidden:NO];
+      [screenBrowser_
+          setCellSize:NSMakeSize(kMultipleScreenWidth, kMultipleScreenHeight)];

[tapted, 2017/05/22 23:54:01]

is this still needed? I don't think it should be here. In the general case, the
size of items determines the number of items the imagebrowser needs to show, and
the number of calls it makes to this delegate method. Changing the size could
trigger more calls to this method, or cause the imagebrowser to discard items it
had returned earlier (possibly even in a loop).

If you really need it, add a comment since it looks really odd. Like (if tested)
"if the user adds or removes a screen while the browser is showing then..."

[qiangchen, 2017/05/23 17:10:14]

The list is dynamically updated in another thread, so it is unsafe to rely on
the logic at initialization stage, as it is likely that at initialization, the
items are not ready yet.

I moved the code to list observer handler. So we can avoid repeatedly doing such
setting at the UI event.

+    } else {
+      [item setTitleHidden:YES];
+      [screenBrowser_
+          setCellSize:NSMakeSize(kSingleScreenWidth, kSingleScreenHeight)];
+    }
+  }
 
   return item;
 }