Replace Dropzone VTKActor by IMGUI

[Ni-g-3l]

Hello !

I try to replace DropZone Actor by a IMGUI window. I'm not ImGUI expert if you see a better way to do it do not hesitate to comment.

Linked issue : #1975

[mwestphal]

Do you think you could put an outline around the text, like its done for the filename ?

[mwestphal]

Other than that, its looking good! Dont hesitate to share such screenshot on discord :)

[mwestphal]

However, how can I update tests in order to match the new dropzone ?

You just need to update the baselines

[Ni-g-3l]

Sorry I don't understand ? Where I can find the example to put outline on text ? because my update on DropText look very similar at what it is done for FileName

[mwestphal]

I think its handled by SetupNextWindow

[mwestphal]

I mean this:

[snoyer]

@Ni-g-3l I would suggest trying absurdly high values for tickThickness and tickLength in order to highlight accuracy/precision issues in the drawing logic.

For example, using:

    constexpr float tickThickness = 25.0f;
    constexpr float tickLength = 40.0f;

this PR's ImGui code shows:

while the previous VTK code shows:

The key point here is that the previous code was drawing rectangles and the new code is drawing thick lines so there's going to be some ±thickness/2 offsets to account for somewhere somehow

(also check to make sure it all still works when resizing the window)

possible fix/improvement

diff --git a/vtkext/private/module/vtkF3DImguiActor.cxx b/vtkext/private/module/vtkF3DImguiActor.cxx
index b54e941c..c386d537 100644
--- a/vtkext/private/module/vtkF3DImguiActor.cxx
+++ b/vtkext/private/module/vtkF3DImguiActor.cxx
@@ -299,8 +299,8 @@ void vtkF3DImguiActor::RenderDropZone()
     constexpr float tickLength = 10.0f;
 
     int dropzonePad = static_cast<int>(std::min(viewport->WorkSize.x, viewport->WorkSize.y) * 0.1);
-    int dropZoneW = viewport->WorkSize.x - dropzonePad;
-    int dropZoneH = viewport->WorkSize.y - dropzonePad;
+    int dropZoneW = viewport->WorkSize.x - dropzonePad * 2;
+    int dropZoneH = viewport->WorkSize.y - dropzonePad * 2;
 
     ::SetupNextWindow(ImVec2(0, 0), viewport->WorkSize);
     ImGui::SetNextWindowBgAlpha(0.f);
@@ -312,7 +312,7 @@ void vtkF3DImguiActor::RenderDropZone()
     ImDrawList* draw_list = ImGui::GetWindowDrawList();
 
     ImVec2 p0(dropzonePad, dropzonePad);
-    ImVec2 p1(dropZoneW, dropZoneH);
+    ImVec2 p1(dropzonePad + dropZoneW, dropzonePad + dropZoneH);
     int tickNumberW = static_cast<int>(std::ceil(dropZoneW / (tickLength * 2.0f)));
     int tickNumberH = static_cast<int>(std::ceil(dropZoneH / (tickLength * 2.0f)));
     double tickSpaceW =
@@ -323,22 +323,24 @@ void vtkF3DImguiActor::RenderDropZone()
     // Draw top and bottom line
     for (float x = p0.x; x < p1.x; x += tickLength + tickSpaceW)
     {
-      draw_list->AddLine(ImVec2(x, p0.y), ImVec2(x + tickLength, p0.y), color, tickThickness);
-      draw_list->AddLine(ImVec2(x, p1.y), ImVec2(x + tickLength, p1.y), color, tickThickness);
+      const float y0 = p0.y + tickThickness / 2.f;
+      const float y1 = p1.y - tickThickness / 2.f;
+      draw_list->AddLine(ImVec2(x, y0), ImVec2(x + tickLength, y0), color, tickThickness);
+      draw_list->AddLine(ImVec2(x, y1), ImVec2(x + tickLength, y1), color, tickThickness);
     }
 
     // Draw left and right line
     for (float y = p0.y; y < p1.y; y += tickLength + tickSpaceH)
     {
-      draw_list->AddLine(ImVec2(p0.x, y), ImVec2(p0.x, y + tickLength), color, tickThickness);
-      draw_list->AddLine(ImVec2(p1.x, y), ImVec2(p1.x, y + tickLength), color, tickThickness);
+      const float x0 = p0.x + tickThickness / 2.f;
+      const float x1 = p1.x - tickThickness / 2.f;
+      draw_list->AddLine(ImVec2(x0, y), ImVec2(x0, y + tickLength), color, tickThickness);
+      draw_list->AddLine(ImVec2(x1, y), ImVec2(x1, y + tickLength), color, tickThickness);
     }
 
     ImGui::End();
 
     ImVec2 dropTextSize = ImGui::CalcTextSize(this->DropText.c_str());
-    dropTextSize.x += 2.f * ImGui::GetStyle().WindowPadding.x;
-    dropTextSize.y += 2.f * ImGui::GetStyle().WindowPadding.y;
 
     ImGui::Begin("DropZoneText", nullptr, flags);
     ImGui::SetCursorPos(ImVec2(viewport->GetWorkCenter().x - 0.5f * dropTextSize.x,

[Ni-g-3l]

I try to fix what you find, with my latest commit

I will fix the CICD tomorow

[snoyer]

@Ni-g-3l I believe you forgot to double the padding at the beginning and ended up trying to compensate for that all along later

[snoyer]

the half-thickness offset you want is only to draw the lines inside the target rectangle rather that on it:

vs

So you just have to to shift the top/bottom lines down/up and the right/left lines left/right, no need to modify/extend the loops:

Suggested change

	double tickBBSizeW = tickLength + tickSpaceW;
	double tickBBSizeH = tickLength + tickSpaceH;
	// Draw top and bottom line
	for (float x = p0.x - tickHalfThickness; x < p1.x - tickBBSizeW; x += tickBBSizeW)
	{
	draw_list->AddLine(ImVec2(x, p0.y), ImVec2(x + tickLength, p0.y), color, tickThickness);
	draw_list->AddLine(ImVec2(x, p1.y), ImVec2(x + tickLength, p1.y), color, tickThickness);
	}
	draw_list->AddLine(ImVec2(p1.x - tickLength, p0.y), ImVec2(p1.x + tickHalfThickness, p0.y),
	color, tickThickness);
	draw_list->AddLine(ImVec2(p1.x - tickLength, p1.y), ImVec2(p1.x + tickHalfThickness, p1.y),
	color, tickThickness);
	// Draw left and right line
	for (float y = p0.y - tickHalfThickness; y < p1.y - tickBBSizeH; y += tickBBSizeH)
	{
	draw_list->AddLine(ImVec2(p0.x, y), ImVec2(p0.x, y + tickLength), color, tickThickness);
	draw_list->AddLine(ImVec2(p1.x, y), ImVec2(p1.x, y + tickLength), color, tickThickness);
	}
	draw_list->AddLine(ImVec2(p0.x, p1.y - tickLength), ImVec2(p0.x, p1.y + tickHalfThickness),
	color, tickThickness);
	draw_list->AddLine(ImVec2(p1.x, p1.y - tickLength), ImVec2(p1.x, p1.y + tickHalfThickness),
	color, tickThickness);
	// Draw top and bottom line
	for (float x = p0.x; x < p1.x; x += tickLength + tickSpaceW)
	{
	const float y0 = p0.y + tickThickness / 2.f;
	const float y1 = p1.y - tickThickness / 2.f;
	draw_list->AddLine(ImVec2(x, y0), ImVec2(x + tickLength, y0), color, tickThickness);
	draw_list->AddLine(ImVec2(x, y1), ImVec2(x + tickLength, y1), color, tickThickness);
	}
	// Draw left and right line
	for (float y = p0.y; y < p1.y; y += tickLength + tickSpaceH)
	{
	const float x0 = p0.x + tickThickness / 2.f;
	const float x1 = p1.x - tickThickness / 2.f;
	draw_list->AddLine(ImVec2(x0, y), ImVec2(x0, y + tickLength), color, tickThickness);
	draw_list->AddLine(ImVec2(x1, y), ImVec2(x1, y + tickLength), color, tickThickness);
	}