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imgui.h: Moved ImGuiListClipper

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omar 2018-11-27 13:58:52 +01:00
parent 8495c931c0
commit ce07d55d1b
1 changed files with 30 additions and 30 deletions
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imgui.h
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@ -1507,6 +1507,36 @@ struct ImGuiStorage
IMGUI_API void BuildSortByKey();
};
// Helper: Manually clip large list of items.
// If you are submitting lots of evenly spaced items and you have a random access to the list, you can perform coarse clipping based on visibility to save yourself from processing those items at all.
// The clipper calculates the range of visible items and advance the cursor to compensate for the non-visible items we have skipped.
// ImGui already clip items based on their bounds but it needs to measure text size to do so. Coarse clipping before submission makes this cost and your own data fetching/submission cost null.
// Usage:
// ImGuiListClipper clipper(1000); // we have 1000 elements, evenly spaced.
// while (clipper.Step())
// for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
// ImGui::Text("line number %d", i);
// - Step 0: the clipper let you process the first element, regardless of it being visible or not, so we can measure the element height (step skipped if we passed a known height as second arg to constructor).
// - Step 1: the clipper infer height from first element, calculate the actual range of elements to display, and position the cursor before the first element.
// - (Step 2: dummy step only required if an explicit items_height was passed to constructor or Begin() and user call Step(). Does nothing and switch to Step 3.)
// - Step 3: the clipper validate that we have reached the expected Y position (corresponding to element DisplayEnd), advance the cursor to the end of the list and then returns 'false' to end the loop.
struct ImGuiListClipper
{
float StartPosY;
float ItemsHeight;
int ItemsCount, StepNo, DisplayStart, DisplayEnd;
// items_count: Use -1 to ignore (you can call Begin later). Use INT_MAX if you don't know how many items you have (in which case the cursor won't be advanced in the final step).
// items_height: Use -1.0f to be calculated automatically on first step. Otherwise pass in the distance between your items, typically GetTextLineHeightWithSpacing() or GetFrameHeightWithSpacing().
// If you don't specify an items_height, you NEED to call Step(). If you specify items_height you may call the old Begin()/End() api directly, but prefer calling Step().
ImGuiListClipper(int items_count = -1, float items_height = -1.0f) { Begin(items_count, items_height); } // NB: Begin() initialize every fields (as we allow user to call Begin/End multiple times on a same instance if they want).
~ImGuiListClipper() { IM_ASSERT(ItemsCount == -1); } // Assert if user forgot to call End() or Step() until false.
IMGUI_API bool Step(); // Call until it returns false. The DisplayStart/DisplayEnd fields will be set and you can process/draw those items.
IMGUI_API void Begin(int items_count, float items_height = -1.0f); // Automatically called by constructor if you passed 'items_count' or by Step() in Step 1.
IMGUI_API void End(); // Automatically called on the last call of Step() that returns false.
};
// Helpers macros to generate 32-bits encoded colors
#ifdef IMGUI_USE_BGRA_PACKED_COLOR
#define IM_COL32_R_SHIFT 16
@ -1547,36 +1577,6 @@ struct ImColor
static ImColor HSV(float h, float s, float v, float a = 1.0f) { float r,g,b; ImGui::ColorConvertHSVtoRGB(h, s, v, r, g, b); return ImColor(r,g,b,a); }
};
// Helper: Manually clip large list of items.
// If you are submitting lots of evenly spaced items and you have a random access to the list, you can perform coarse clipping based on visibility to save yourself from processing those items at all.
// The clipper calculates the range of visible items and advance the cursor to compensate for the non-visible items we have skipped.
// ImGui already clip items based on their bounds but it needs to measure text size to do so. Coarse clipping before submission makes this cost and your own data fetching/submission cost null.
// Usage:
// ImGuiListClipper clipper(1000); // we have 1000 elements, evenly spaced.
// while (clipper.Step())
// for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
// ImGui::Text("line number %d", i);
// - Step 0: the clipper let you process the first element, regardless of it being visible or not, so we can measure the element height (step skipped if we passed a known height as second arg to constructor).
// - Step 1: the clipper infer height from first element, calculate the actual range of elements to display, and position the cursor before the first element.
// - (Step 2: dummy step only required if an explicit items_height was passed to constructor or Begin() and user call Step(). Does nothing and switch to Step 3.)
// - Step 3: the clipper validate that we have reached the expected Y position (corresponding to element DisplayEnd), advance the cursor to the end of the list and then returns 'false' to end the loop.
struct ImGuiListClipper
{
float StartPosY;
float ItemsHeight;
int ItemsCount, StepNo, DisplayStart, DisplayEnd;
// items_count: Use -1 to ignore (you can call Begin later). Use INT_MAX if you don't know how many items you have (in which case the cursor won't be advanced in the final step).
// items_height: Use -1.0f to be calculated automatically on first step. Otherwise pass in the distance between your items, typically GetTextLineHeightWithSpacing() or GetFrameHeightWithSpacing().
// If you don't specify an items_height, you NEED to call Step(). If you specify items_height you may call the old Begin()/End() api directly, but prefer calling Step().
ImGuiListClipper(int items_count = -1, float items_height = -1.0f) { Begin(items_count, items_height); } // NB: Begin() initialize every fields (as we allow user to call Begin/End multiple times on a same instance if they want).
~ImGuiListClipper() { IM_ASSERT(ItemsCount == -1); } // Assert if user forgot to call End() or Step() until false.
IMGUI_API bool Step(); // Call until it returns false. The DisplayStart/DisplayEnd fields will be set and you can process/draw those items.
IMGUI_API void Begin(int items_count, float items_height = -1.0f); // Automatically called by constructor if you passed 'items_count' or by Step() in Step 1.
IMGUI_API void End(); // Automatically called on the last call of Step() that returns false.
};
//-----------------------------------------------------------------------------
// Draw List
// Hold a series of drawing commands. The user provides a renderer for ImDrawData which essentially contains an array of ImDrawList.