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HTML rendering is abstracted from graphics libraries via THtCanvas class. There are several implementations that can be selected globally or for certain component or document. Global variables (defined in htcanvas):

 

•HtDefaultCanvasClass - default canvas for VCL

•HtUIDefaultCanvasClass - default canvas for VCL UI controls (Checkbox, Radio)

•HtFMXDefaultCanvasClass - default class for FMX

 

THtDocument and THtPanel has CanvasClass properties to set preferred canvas.

 

There are the following canvas implementations:

 

VCL

 

THtCanvasDX - rendering using DIrect2D library, best performance and quality, recommended as default class on Windows. May not work on XP. htcanvadx unit. When using DX canvas turn off DoubleBuffered property for form and parent components.

THtCanvasGP - rendeding using GDI+ library. Good quality but bot so fast as DX. htcanvasgdip unit.

THtCanvasGDI - rendering using GDI. Do not support antialiasing and has integer coordinates. htcanvasgdi unit.

THtCanvasSKIA - good quality and speed, but not so fast as DX. htcanvasskia unit.

THtCanvasText - plain text canvas. htcanvstext unit.

THtCanvasOpenGL - OpenGL canvas, good for displaying large vector data. Work only in window, do use as default canvas.

 

FMX

 

THtCanvasFMX - default FMX canvas. On windows may use D2D directly for better speed and more features. fmx.htcanvasfmx unit.

THtCanvasOSX - native OSX canvas. Faster than default. fmx.htcanvasOSX unit. Note that it cannot be used when GlobalUseMetal is set to true

THtCanvasAndroid - native Android canvas, faster than default and better quality. fmx.htcamvasAndroid unit.

THtCanvasiOS - native iOS canvas. faster than default and better quality. fmx.htcanvasiOS unit.

 

To access canvas from document, use Document.Surface property.