A Qt/OpenGL-based implementation of a heap history visualisation UI in along the lines of Gerardo Richarte's HeapDraw (for more details, check http://actes.sstic.org/SSTIC07/Rump_sessions/SSTIC07-rump-Richarte-Heap_Massaging.pdf)

The tool had been reimplemented by various people in various places a few times, usually in a hackish / nonscalable manner. zynamics used to hand source code for a JOGL-based UI out with some of our trainings, but that tool is not easily portable to modern OpenGL or 64-bit address spaces.

Other common mistakes include:

• Not using OpenGL to render lots of rectangles.
• Using floats or other low-precision coordinates to represent rectangle corners and hence suffering from rounding errors.
• Not using a language that can deal with a couple million rectangles.

The codebase in this repository has the following goals:

• Fast and scalable to 20m+ allocations. Haven't tried, but should work.
• As precise as possible. Use precise integer arithmetic as much as possible to avoid rounding errors shifting rectangles around.
• Useable. This will take some time.

Instructions for the moment:

• Build using stock QtCreator.
• You will need: libgflags-dev mesa-common-dev libqt4-opengl-dev
• The current trunk will simply try to load /tmp/heap.json - use the enclosed json file as an example.

A million tasks are still left to do. Useful things that should be added:

• Code to display tooltips when the mouse hovers over a block.
• Code to highlight a block when it is clicked / selected.
• Code to add horizontal red lines, too.
• Code to select all blocks that are modified between two events.
• ...

Contributions very welcome.

Basic controls:

• CTRL + wheel: Zoom in / out
• Click + drag: Pan diagram
• CTRL + shift + wheel: Squash / stretch horizontally
• shift + wheel: Squash / stretch vertically

Cheers, Halvar Flake / Thomas Dullien