Replace QPainter with Blend2D in CMapIMG

CLAUDE.md

@@ -150,6 +150,44 @@ Only local BRouter supports fast (on-the-fly) routing. Online BRouter and Routin
 
 ---
 
+## Architecture: CMapIMG Blend2D hybrid renderer
+
+`CMapIMG::draw()` (the Garmin IMG renderer) rasterises geometry with **Blend2D** and
+keeps **text/labels on QPainter**. Dependency: `find_package(blend2d REQUIRED)` (root
+CMakeLists), linked as `blend2d::blend2d`.
+
+**Phase split in `draw()`:**
+1. *Geometry phase (Blend2D):* `drawPolygons`, `drawPolylines`, `drawPoints`, `drawPois`,
+   `loadVisibleData` — all take `BLContext&`. They also collect text into `textpaths`/`labels`.
+2. *Text phase (QPainter):* `drawText`, `drawLabels` — still take `QPainter&`. Qt's font
+   matching/shaping has no Blend2D equivalent and text is a negligible share of draw time.
+
+**Key invariants (easy to break):**
+- **Premultiplied round-trip.** The shared buffer is `Format_ARGB32` (non-premultiplied);
+  Blend2D only renders `BL_FORMAT_PRGB32`. `draw()` does `convertTo(Format_ARGB32_Premultiplied)`
+  at the start and `convertTo(Format_ARGB32)` at the end so the format change stays invisible
+  to the rest of the map stack. (Optional follow-up: make `IDrawContext` allocate premultiplied
+  buffers to drop both conversions.)
+- **Synchronous context only.** `BLContext(blBuf)` defaults to synchronous rendering, so source
+  images for blits (`img2line` segments, icons) and pattern tiles may be temporaries — they are
+  read before the call returns. Do **not** switch to a multithreaded/async `BLContextCreateInfo`
+  without making those sources outlive `ctx.end()`.
+- **`ctx.end()` before the QPainter phase** — flushes Blend2D pixels before QPainter touches the
+  same image.
+- **Both phases re-apply `translate(-pp)`** (the buffer-vs-screen offset); the single shared
+  painter that used to do it once is gone.
+
+**Helpers (anonymous namespace in `CMapIMG.cpp`):** `applyPen` (QPen→stroke state incl. Qt dash
+styles, returns false for `Qt::NoPen`), `polyToPath`, `toBLColor`, `blitQImage`/`blitBullet`
+(convert to premultiplied on the fly), `brushToTile` (texture/hatch QBrush → repeating `BLPattern`
+tile). `drawPolygons` sets `BL_FILL_RULE_EVEN_ODD` to match `QPainter::drawPolygon`.
+
+The pixmap-along-line loop indexes polyline vertices directly (arc-length breakpoints coincide
+with vertices), replacing the old `QPainterPath::pointAtPercent` walk; angles use `std::atan2`
+(radians) since `BLContext::rotate` takes radians, not degrees.
+
+---
+
 ## Architecture: tree item delegates
 
 The three `QStyledItemDelegate` subclasses used by the tree views:

CMakeLists.txt

@@ -229,6 +229,50 @@ endif(NOT ALGLIB_FOUND AND BUILD_QMAPSHACK)
 
 add_definitions(-DHELPPATH=${HTML_INSTALL_DIR})
 
+include(FetchContent)
+
+###############################################################################################
+# Get Tracy
+###############################################################################################
+set(TRACY_GIT_TAG  "master" CACHE STRING "Tracy git revision to fetch")
+FetchContent_Declare (
+    tracy
+    GIT_REPOSITORY https://github.com/wolfpld/tracy.git
+    GIT_TAG master
+    GIT_SHALLOW TRUE
+    GIT_PROGRESS TRUE
+)
+FetchContent_MakeAvailable(tracy)
+
+###############################################################################################
+# Get Blend2D and it's dependency AsmJit
+###############################################################################################
+set(ASMJIT_GIT_TAG  "master" CACHE STRING "AsmJit git revision to fetch")
+set(BLEND2D_GIT_TAG "master" CACHE STRING "Blend2D git revision to fetch")
+
+# asmjit is Blend2D's JIT backend. Fetch its sources only: SOURCE_SUBDIR points at a
+# directory with no CMakeLists.txt so FetchContent_MakeAvailable populates without calling
+# add_subdirectory(). Blend2D adds asmjit itself (via ASMJIT_DIR) and, because we build it
+# statically, embeds it directly into the blend2d library.
+FetchContent_Declare(asmjit
+    GIT_REPOSITORY https://github.com/asmjit/asmjit.git
+    GIT_TAG        ${ASMJIT_GIT_TAG}
+    GIT_SHALLOW    TRUE
+    GIT_PROGRESS TRUE
+    SOURCE_SUBDIR  __populate_only__
+)
+FetchContent_MakeAvailable(asmjit)
+set(ASMJIT_DIR "${asmjit_SOURCE_DIR}" CACHE PATH "AsmJit source directory" FORCE)
+
+set(BLEND2D_STATIC TRUE)
+FetchContent_Declare(blend2d
+    GIT_REPOSITORY https://github.com/blend2d/blend2d.git
+    GIT_TAG        ${BLEND2D_GIT_TAG}
+    GIT_SHALLOW    TRUE
+    GIT_PROGRESS TRUE
+)
+FetchContent_MakeAvailable(blend2d)
+
 ###############################################################################################
 # Create library from Garmin's FIT SDK
 ###############################################################################################

src/qmapshack/CMakeLists.txt

@@ -1035,6 +1035,8 @@ target_link_libraries(${APPLICATION_NAME}
     ${ALGLIB_LIBRARIES}
     QuaZip::QuaZip
     GarminFit
+    Tracy::TracyClient
+    blend2d::blend2d
 )
 
 if(APPLE)

src/qmapshack/canvas/IDrawContext.cpp

@@ -19,6 +19,7 @@
 #include "canvas/IDrawContext.h"
 
 #include <QtWidgets>
+#include <tracy/Tracy.hpp>
 
 #define BUFFER_BORDER 50
 
@@ -258,6 +259,7 @@ void IDrawContext::convertPx2Rad(QPointF& p) const {
 }
 
 void IDrawContext::convertRad2Px(QPointF& p) const {
+  ZoneScoped;
   mutex.lock();  // --------- start serialize with thread
 
   QPointF f = focus;

src/qmapshack/map/CMapDraw.cpp

@@ -20,6 +20,7 @@
 
 #include <QtGui>
 #include <QtWidgets>
+#include <tracy/Tracy.hpp>
 
 #include "CMainWindow.h"
 #include "canvas/CCanvas.h"
@@ -405,9 +406,11 @@ void CMapDraw::drawt(IDrawContext::buffer_t& currentBuffer) /* override */
       }
 
       item->setProcessing(true);
+      FrameMarkStart("imgDraw");
       item->getMapfile()->draw(currentBuffer);
       item->setProcessing(false);
       seenActiveMap = true;
+      FrameMarkEnd("imgDraw");
     }
   }
   CMapItem::mutexActiveMaps.unlock();