HaikuDepot TextView: add support for hyperlinks/clikable areas

Specific text spans can be assigned a cursor and BMessage to send when
they are clicked. This allows for implementing hyperlinks, specific
popup menus, and clickable text of any type.

With some extra work it can also be used to implement spell checking
suggestions, buttons, and so on.

Change-Id: I390e0c44656da76a950c432bdd934bd51af49baf
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7130
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

src/apps/haikudepot/textview/TextDocument.cpp

@@ -180,6 +180,48 @@ TextDocument::CharacterStyleAt(int32 textOffset) const
 }
 
 
+const BMessage*
+TextDocument::ClickMessageAt(int32 textOffset) const
+{
+	int32 paragraphOffset;
+	const Paragraph& paragraph = ParagraphAt(textOffset, paragraphOffset);
+
+	textOffset -= paragraphOffset;
+	int32 index;
+	int32 count = paragraph.CountTextSpans();
+
+	for (index = 0; index < count; index++) {
+		const TextSpan& span = paragraph.TextSpanAtIndex(index);
+		if (textOffset - span.CountChars() < 0)
+			return span.ClickMessage();
+		textOffset -= span.CountChars();
+	}
+
+	return NULL;
+}
+
+
+BCursor
+TextDocument::CursorAt(int32 textOffset) const
+{
+	int32 paragraphOffset;
+	const Paragraph& paragraph = ParagraphAt(textOffset, paragraphOffset);
+
+	textOffset -= paragraphOffset;
+	int32 index;
+	int32 count = paragraph.CountTextSpans();
+
+	for (index = 0; index < count; index++) {
+		const TextSpan& span = paragraph.TextSpanAtIndex(index);
+		if (textOffset - span.CountChars() < 0)
+			return span.Cursor();
+		textOffset -= span.CountChars();
+	}
+
+	return BCursor((BMessage*)NULL);
+}
+
+
 const ParagraphStyle&
 TextDocument::ParagraphStyleAt(int32 textOffset) const
 {

src/apps/haikudepot/textview/TextDocument.h

@@ -55,6 +55,8 @@ public:
 			// Style access
 			const CharacterStyle& CharacterStyleAt(int32 textOffset) const;
 			const ParagraphStyle& ParagraphStyleAt(int32 textOffset) const;
+			BCursor				CursorAt(int32 textOffset) const;
+			const BMessage*		ClickMessageAt(int32 textOffset) const;
 
 			int32				CountParagraphs() const;
 			const Paragraph&	ParagraphAtIndex(int32 index) const;

src/apps/haikudepot/textview/TextDocumentView.cpp

@@ -137,14 +137,28 @@ TextDocumentView::MakeFocus(bool focus)
 void
 TextDocumentView::MouseDown(BPoint where)
 {
+	BMessage* currentMessage = NULL;
+	if (Window() != NULL)
+		currentMessage = Window()->CurrentMessage();
+
+	// First of all, check for links and other clickable things
+	bool unused;
+	int32 offset = fTextDocumentLayout.TextOffsetAt(where.x, where.y, unused);
+	const BMessage* message = fTextDocument->ClickMessageAt(offset);
+	if (message != NULL) {
+		BMessage clickMessage(*message);
+		clickMessage.Append(*currentMessage);
+		Invoke(&clickMessage);
+	}
+
 	if (!fSelectionEnabled)
 		return;
 
 	MakeFocus();
 
 	int32 modifiers = 0;
-	if (Window() != NULL && Window()->CurrentMessage() != NULL)
-		Window()->CurrentMessage()->FindInt32("modifiers", &modifiers);
+	if (currentMessage != NULL)
+		currentMessage->FindInt32("modifiers", &modifiers);
 
 	fMouseDown = true;
 	SetMouseEventMask(B_POINTER_EVENTS, B_LOCK_WINDOW_FOCUS);
@@ -165,11 +179,22 @@ void
 TextDocumentView::MouseMoved(BPoint where, uint32 transit,
 	const BMessage* dragMessage)
 {
+	BCursor cursor(B_CURSOR_ID_I_BEAM);
+
+	if (transit != B_EXITED_VIEW) {
+		bool unused;
+		int32 offset = fTextDocumentLayout.TextOffsetAt(where.x, where.y, unused);
+		const BCursor& newCursor = fTextDocument->CursorAt(offset);
+		if (newCursor.InitCheck() == B_OK) {
+			cursor = newCursor;
+			SetViewCursor(&cursor);
+		}
+	}
+
 	if (!fSelectionEnabled)
 		return;
 
-	BCursor iBeamCursor(B_CURSOR_ID_I_BEAM);
-	SetViewCursor(&iBeamCursor);
+	SetViewCursor(&cursor);
 
 	if (fMouseDown)
 		SetCaret(where, true);

src/apps/haikudepot/textview/TextDocumentView.h

@@ -5,6 +5,7 @@
 #ifndef TEXT_DOCUMENT_VIEW_H
 #define TEXT_DOCUMENT_VIEW_H
 
+#include <Invoker.h>
 #include <String.h>
 #include <View.h>
 
@@ -17,7 +18,7 @@ class BClipboard;
 class BMessageRunner;
 
 
-class TextDocumentView : public BView {
+class TextDocumentView : public BView, public BInvoker {
 public:
 								TextDocumentView(const char* name = NULL);
 	virtual						~TextDocumentView();

src/apps/haikudepot/textview/TextSpan.cpp

@@ -10,7 +10,9 @@ TextSpan::TextSpan()
 	:
 	fText(),
 	fCharCount(0),
-	fStyle()
+	fStyle(),
+	fCursor((BMessage*)NULL),
+	fClickMessage()
 {
 }
 
@@ -19,7 +21,9 @@ TextSpan::TextSpan(const BString& text, const CharacterStyle& style)
 	:
 	fText(text),
 	fCharCount(text.CountChars()),
-	fStyle(style)
+	fStyle(style),
+	fCursor((BMessage*)NULL),
+	fClickMessage()
 {
 }
 
@@ -28,7 +32,9 @@ TextSpan::TextSpan(const TextSpan& other)
 	:
 	fText(other.fText),
 	fCharCount(other.fCharCount),
-	fStyle(other.fStyle)
+	fStyle(other.fStyle),
+	fCursor(other.fCursor),
+	fClickMessage(other.fClickMessage)
 {
 }
 
@@ -39,6 +45,8 @@ TextSpan::operator=(const TextSpan& other)
 	fText = other.fText;
 	fCharCount = other.fCharCount;
 	fStyle = other.fStyle;
+	fCursor = other.fCursor;
+	fClickMessage = other.fClickMessage;
 
 	return *this;
 }
@@ -49,7 +57,10 @@ TextSpan::operator==(const TextSpan& other) const
 {
 	return fCharCount == other.fCharCount
 		&& fStyle == other.fStyle
-		&& fText == other.fText;
+		&& fText == other.fText
+		&& fCursor == other.fCursor
+		&& fClickMessage.what == other.fClickMessage.what
+		&& fClickMessage.HasSameData(other.fClickMessage);
 }
 
 
@@ -75,6 +86,20 @@ TextSpan::SetStyle(const CharacterStyle& style)
 }
 
 
+void
+TextSpan::SetCursor(const BCursor& cursor)
+{
+	fCursor = cursor;
+}
+
+
+void
+TextSpan::SetClickMessage(BMessage* message)
+{
+	fClickMessage = *message;
+}
+
+
 bool
 TextSpan::Append(const BString& text)
 {

src/apps/haikudepot/textview/TextSpan.h

@@ -6,6 +6,7 @@
 #define TEXT_SPAN_H
 
 
+#include <Cursor.h>
 #include <String.h>
 
 #include "CharacterStyle.h"
@@ -39,6 +40,12 @@ public:
 
 			TextSpan			SubSpan(int32 start, int32 count) const;
 
+			void				SetCursor(const BCursor& cursor);
+	inline	const BCursor&		Cursor() const
+									{ return fCursor; }
+			void				SetClickMessage(BMessage* message);
+	inline	const BMessage*		ClickMessage() const
+									{ return fClickMessage.IsEmpty() ? NULL : &fClickMessage; }
 private:
 			void				_TruncateInsert(int32& start) const;
 			void				_TruncateRemove(int32& start,
@@ -48,6 +55,9 @@ private:
 			BString				fText;
 			int32				fCharCount;
 			CharacterStyle		fStyle;
+
+			BCursor				fCursor;
+			BMessage			fClickMessage;
 };