Merge #6544

6544: make envelope editor resizeable by dragging r=def- a=Marmare314


![resizeable-editor](https://user-images.githubusercontent.com/49279081/235273201-5ee620c3-3784-49d1-ac0c-3bc3d5aca440.gif)


## Checklist

- [x] Tested the change ingame
- [x] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test (especially base/) or added coverage to integration test
- [x] Considered possible null pointers and out of bounds array indexing
- [x] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: marmare314 <49279081+Marmare314@users.noreply.github.com>

src/game/editor/editor.cpp

@@ -336,6 +336,8 @@ ColorRGBA CEditor::GetButtonColor(const void *pID, int Checked)
 
 	switch(Checked)
 	{
+	case 8: // invisible
+		return ColorRGBA(0, 0, 0, 0);
 	case 7: // selected + game layers
 		if(UI()->HotItem() == pID)
 			return ColorRGBA(1, 0, 0, 0.4f);
@@ -5221,14 +5223,9 @@ void CEditor::RenderStatusbar(CUIRect View)
 	CUIRect Button;
 	View.VSplitRight(60.0f, &View, &Button);
 	static int s_EnvelopeButton = 0;
-	int MouseButton = DoButton_Editor(&s_EnvelopeButton, "Envelopes", m_ShowEnvelopeEditor, &Button, 0, "Toggles the envelope editor.");
-	if(MouseButton == 2)
-		m_ShowEnvelopeEditor = (m_ShowEnvelopeEditor + 3) % 4;
-	else if(MouseButton == 1)
-		m_ShowEnvelopeEditor = (m_ShowEnvelopeEditor + 1) % 4;
-
-	if(MouseButton)
+	if(DoButton_Editor(&s_EnvelopeButton, "Envelopes", m_ShowEnvelopeEditor, &Button, 0, "Toggles the envelope editor."))
 	{
+		m_ShowEnvelopeEditor ^= 1;
 		m_ShowServerSettingsEditor = false;
 	}
 
@@ -5237,7 +5234,7 @@ void CEditor::RenderStatusbar(CUIRect View)
 	static int s_SettingsButton = 0;
 	if(DoButton_Editor(&s_SettingsButton, "Server settings", m_ShowServerSettingsEditor, &Button, 0, "Toggles the server settings editor."))
 	{
-		m_ShowEnvelopeEditor = 0;
+		m_ShowEnvelopeEditor = false;
 		m_ShowServerSettingsEditor ^= 1;
 	}
 
@@ -5321,6 +5318,12 @@ void CEditor::RenderEnvelopeEditor(CUIRect View)
 	if(m_SelectedEnvelope >= 0 && m_SelectedEnvelope < (int)m_Map.m_vpEnvelopes.size())
 		pEnvelope = m_Map.m_vpEnvelopes[m_SelectedEnvelope];
 
+	CUIRect DragBar = {
+		View.x,
+		View.y - 2.0f, // use margin
+		View.w,
+		22.0f,
+	};
 	CUIRect ToolBar, CurveBar, ColorBar;
 	View.HSplitTop(15.0f, &ToolBar, &View);
 	View.HSplitTop(15.0f, &CurveBar, &View);
@@ -5329,6 +5332,47 @@ void CEditor::RenderEnvelopeEditor(CUIRect View)
 
 	bool CurrentEnvelopeSwitched = false;
 
+	// do the dragbar
+	{
+		enum
+		{
+			OP_NONE,
+			OP_DRAG_HEADER,
+			OP_CLICK_HEADER
+		};
+		static int s_Operation = 0;
+		static float s_InitialMouseY = 0.0f;
+		static float s_InitialMouseOffsetY = 0.0f;
+
+		static int s_DragBar = 0;
+		bool Clicked;
+		bool Abrupted;
+		if(int Result = DoButton_DraggableEx(&s_DragBar, "", 8, &DragBar, &Clicked, &Abrupted, 0, "Change the size of the editor by dragging."))
+		{
+			if(s_Operation == OP_NONE && Result == 1)
+			{
+				s_InitialMouseY = UI()->MouseY();
+				s_InitialMouseOffsetY = UI()->MouseY() - DragBar.y;
+				s_Operation = OP_CLICK_HEADER;
+			}
+
+			if(Abrupted)
+				s_Operation = OP_NONE;
+
+			if(s_Operation == OP_CLICK_HEADER && absolute(UI()->MouseY() - s_InitialMouseY) > 5)
+				s_Operation = OP_DRAG_HEADER;
+
+			if(s_Operation == OP_DRAG_HEADER)
+			{
+				if(Clicked)
+					s_Operation = OP_NONE;
+
+				m_EnvelopeEditorSplit = s_InitialMouseOffsetY + View.y + View.h - UI()->MouseY();
+				m_EnvelopeEditorSplit = clamp(m_EnvelopeEditorSplit, 100.0f, 400.0f);
+			}
+		}
+	}
+
 	// do the toolbar
 	{
 		CUIRect Button;
@@ -6066,14 +6110,7 @@ void CEditor::Render()
 		View.HSplitBottom(16.0f, &View, &StatusBar);
 
 		if(m_ShowEnvelopeEditor && !m_ShowPicker)
-		{
-			float Size = 125.0f;
-			if(m_ShowEnvelopeEditor == 2)
-				Size *= 2.0f;
-			else if(m_ShowEnvelopeEditor == 3)
-				Size *= 3.0f;
-			View.HSplitBottom(Size, &View, &ExtraEditor);
-		}
+			View.HSplitBottom(m_EnvelopeEditorSplit, &View, &ExtraEditor);
 
 		if(m_ShowServerSettingsEditor && !m_ShowPicker)
 			View.HSplitBottom(250.0f, &View, &ExtraEditor);

src/game/editor/editor.h

@@ -808,7 +808,8 @@ public:
 		m_AnimateTime = 0;
 		m_AnimateSpeed = 1;
 
-		m_ShowEnvelopeEditor = 0;
+		m_ShowEnvelopeEditor = false;
+		m_EnvelopeEditorSplit = 250.0f;
 		m_ShowServerSettingsEditor = false;
 
 		m_ShowEnvelopePreview = SHOWENV_NONE;
@@ -1060,7 +1061,8 @@ public:
 	float m_AnimateTime;
 	float m_AnimateSpeed;
 
-	int m_ShowEnvelopeEditor;
+	bool m_ShowEnvelopeEditor;
+	float m_EnvelopeEditorSplit;
 
 	enum EShowEnvelope
 	{