HaikuDepot: begin support for multiple screenshots

* Initial support for displaying multiple screenshots for packages
  which have more than one. Still rough and unfinished.

  Screenshot window now has a toolbar with prev/next buttons and
  a busy loading indicator. Switching through the screenshots works.

  There's currently a server-side bug which makes all data turn up
  15 times in the JSON file, so please don't report a bug about
  HaikuDepot showing 15 or 30 screenshots available when it's really
  just 1 or 2 :)

  Still to be done: toolbar icons instead of text labels; better
  handling of screenshot window resizing; maybe thumbnails of
  screenshots and preloading other screenshots in the background.
  Main window also needs a way to indicate that there are more
  screenshots than the one thumbnail, needs some more thought about
  how that might look.

  This concludes my HaikuDepot commits from the coding sprint at
  KDC 2017 Toulouse!

src/apps/haikudepot/ui/ScreenshotWindow.cpp

@@ -12,7 +12,9 @@
 #include <Autolock.h>
 #include <Catalog.h>
 #include <LayoutBuilder.h>
+#include <StringView.h>
 
+#include "BarberPole.h"
 #include "BitmapView.h"
 #include "WebAppInterface.h"
 
@@ -31,11 +33,31 @@ ScreenshotWindow::ScreenshotWindow(BWindow* parent, BRect frame)
 	BWindow(frame, B_TRANSLATE("Screenshot"),
 		B_FLOATING_WINDOW_LOOK, B_FLOATING_SUBSET_WINDOW_FEEL,
 		B_ASYNCHRONOUS_CONTROLS | B_AUTO_UPDATE_SIZE_LIMITS),
+	fNumScreenshots(0),
 	fDownloadPending(false),
 	fWorkerThread(-1)
 {
 	AddToSubset(parent);
 
+	atomic_set(&fCurrentScreenshotIndex, 0);
+
+	fBarberPole = new BarberPole("barber pole");
+	fBarberPole->SetExplicitMaxSize(BSize(200, B_SIZE_UNLIMITED));
+
+	fIndexView = new BStringView("screenshot index", NULL);
+
+	fToolBar = new BToolBar();
+	fToolBar->AddAction(MSG_PREVIOUS_SCREENSHOT, this, NULL /* todo: icon */,
+		B_TRANSLATE("Show previous screenshot"),
+		B_TRANSLATE("Previous"));
+	fToolBar->AddAction(MSG_NEXT_SCREENSHOT, this, NULL /* todo: icon */,
+		B_TRANSLATE("Show next screenshot"),
+		B_TRANSLATE("Next"));
+	fToolBar->AddGlue();
+	fToolBar->AddView(fIndexView);
+	fToolBar->AddGlue();
+	fToolBar->AddView(fBarberPole);
+
 	fScreenshotView = new BitmapView("screenshot view");
 	fScreenshotView->SetExplicitMaxSize(
 		BSize(B_SIZE_UNLIMITED, B_SIZE_UNLIMITED));
@@ -44,7 +66,10 @@ ScreenshotWindow::ScreenshotWindow(BWindow* parent, BRect frame)
 	groupView->SetViewColor(kBackgroundColor);
 
 	// Build layout
-	BLayoutBuilder::Group<>(this, B_VERTICAL)
+	BLayoutBuilder::Group<>(this, B_VERTICAL, 0)
+		.SetInsets(0, 5, 0, 0)
+		.Add(fToolBar)
+		.AddStrut(5)
 		.AddGroup(groupView)
 			.Add(fScreenshotView)
 			.SetInsets(B_USE_WINDOW_INSETS)
@@ -83,6 +108,28 @@ void
 ScreenshotWindow::MessageReceived(BMessage* message)
 {
 	switch (message->what) {
+		case MSG_NEXT_SCREENSHOT:
+		{
+			atomic_add(&fCurrentScreenshotIndex, 1);
+			_UpdateToolBar();
+			_DownloadScreenshot();
+			break;
+		}
+
+		case MSG_PREVIOUS_SCREENSHOT:
+			atomic_add(&fCurrentScreenshotIndex, -1);
+			_UpdateToolBar();
+			_DownloadScreenshot();
+			break;
+
+		case MSG_DOWNLOAD_START:
+			fBarberPole->Start();
+			break;
+
+		case MSG_DOWNLOAD_STOP:
+			fBarberPole->Stop();
+			break;
+
 		default:
 			BWindow::MessageReceived(message);
 			break;
@@ -113,6 +160,11 @@ ScreenshotWindow::SetPackage(const PackageInfoRef& package)
 		_DownloadScreenshot();
 	}
 	SetTitle(title);
+
+	atomic_set(&fCurrentScreenshotIndex, 0);
+	fNumScreenshots = fPackage->ScreenshotInfos().CountItems();
+
+	_UpdateToolBar();
 }
 
 
@@ -200,14 +252,21 @@ ScreenshotWindow::_DownloadThread()
 	// Obtain the correct code for the screenshot to display
 	// TODO: Once navigation buttons are added, we could use the
 	// ScreenshotInfo at the "current" index.
-	const ScreenshotInfo& info = screenshotInfos.ItemAtFast(0);
+	const ScreenshotInfo& info = screenshotInfos.ItemAtFast(
+		atomic_get(&fCurrentScreenshotIndex));
 
 	BMallocIO buffer;
 	WebAppInterface interface;
 
+	BMessenger messenger(this);
+	messenger.SendMessage(MSG_DOWNLOAD_START);
+
 	// Retrieve screenshot from web-app
 	status_t status = interface.RetrieveScreenshot(info.Code(),
 		info.Width(), info.Height(), &buffer);
+
+	messenger.SendMessage(MSG_DOWNLOAD_STOP);
+
 	if (status == B_OK && Lock()) {
 		printf("got screenshot");
 		fScreenshot = BitmapRef(new(std::nothrow)SharedBitmap(buffer), true);
@@ -229,3 +288,20 @@ ScreenshotWindow::_ResizeToFitAndCenter()
 	ResizeTo(minWidth, minHeight);
 	CenterOnScreen();
 }
+
+
+void
+ScreenshotWindow::_UpdateToolBar()
+{
+	int32 currentIndex = atomic_get(&fCurrentScreenshotIndex);
+	fToolBar->SetActionEnabled(MSG_PREVIOUS_SCREENSHOT,
+		currentIndex > 0);
+	fToolBar->SetActionEnabled(MSG_NEXT_SCREENSHOT,
+		currentIndex < fNumScreenshots - 2);
+
+	BString text;
+	text << currentIndex + 1;
+	text << " / ";
+	text << fNumScreenshots;
+	fIndexView->SetText(text);
+}

src/apps/haikudepot/ui/ScreenshotWindow.h

@@ -7,12 +7,23 @@
 
 #include <Locker.h>
 #include <Messenger.h>
+#include <ToolBar.h>
 #include <Window.h>
 
 #include "PackageInfo.h"
 
 
+class BarberPole;
 class BitmapView;
+class BStringView;
+
+
+enum {
+	MSG_NEXT_SCREENSHOT     = 'nscr',
+	MSG_PREVIOUS_SCREENSHOT = 'pscr',
+	MSG_DOWNLOAD_START      = 'dlst',
+	MSG_DOWNLOAD_STOP       = 'dlsp',
+};
 
 
 class ScreenshotWindow : public BWindow {
@@ -39,14 +50,22 @@ private:
 			void				_DownloadThread();
 
 			void				_ResizeToFitAndCenter();
+			void				_UpdateToolBar();
 
 private:
 			BMessenger			fOnCloseTarget;
 			BMessage			fOnCloseMessage;
 
+			BToolBar*			fToolBar;
+			BarberPole*			fBarberPole;
+			BStringView*		fIndexView;
+
 			BitmapRef			fScreenshot;
 			BitmapView*			fScreenshotView;
 
+			int32				fNumScreenshots;
+			int32				fCurrentScreenshotIndex; // atomic
+
 			PackageInfoRef		fPackage;
 			bool				fDownloadPending;