Tuesday, November 17, 2009


TCanvas 有一個 property , 一般表示成 TCanvas::Pixels, 是我們常會用到的, Pixels 這個 property 可以讀出, 也可以寫入某個特定位置的色彩值, 因此這個 property 的類別為 TColor。在 BCB Help 中的說明如下:
Specifies the color of the pixels within the current ClipRect.

__property TColor Pixels[int X][int Y] = {read=GetPixel, write=SetPixel};

Read Pixels to learn the color on the drawing surface at a specific pixel position within the current clipping region. If the position is outside the clipping rectangle, reading the value of Pixels returns -1.

Write Pixels to change the color of individual pixels on the drawing surface. Use Pixels for detailed effects on an image. Pixels may also be used to determine the color that should be used for the FillRect method.

Not every device context supports the Pixels property. Reading the Pixels property for such a device context will return a value of -1. Setting the Pixels property for such a device context does nothing.

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