Implementing compound shadows with CExtWndShadow

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Introduction

This article introduces a CExtWndShadow class, which should enable you to easily draw compound shadows anywhere you want.

The class is partially based on the CExtWndShadow class presented in the freeware version of the Prof-UIS library available here.

How to use it

The CExtWndShadow class is simple to use. To add it to your project, please follow the steps below:

1. Put its source files (CExtWndShadow.cpp and CExtWndShadow.h) into the proper folder and add their file names to your Visual Studio project.
2. Include its header to the appropriate header file. If you plan to use CExtWndShadow in more than one place, it's reasonable to add it to the stdafx.h file.

   #include "CExtWndShadow.h"

Method description

bool Paint(
    CDC & dc,
    const CRect & rcWndArea,
    UINT nShadowSize = DEF_SHADOW_SIZE,
    UINT nBr0 = DEF_BRIGHTNESS_MIN,
    UINT nBr1 = DEF_BRIGHTNESS_MAX,
    bool bEnablePhotos = true
);

Draws the shadow.

Parameters

• CDC & dc

  Reference to the device context that is used for drawing the shadow.

• const CRect & rcWndArea

  Reference to the rectangular area in which the shadow is drawn.

• UINT nShadowSize

  Size of the shadow in pixels, which is the same for the width and height.

• UINT nBr0

  Minimum brightness of the shadow, which must be in the range 0 to 10.

• UINT nBr1

  Maximum brightness of the shadow, which must be in the range 0 to 10.

• bool bEnablePhotos

  If bEnablePhotos is set to true, specifies that the shadow algorithm is used at first and then the image is just displayed; otherwise, the shadow algorithm is used every time.

Return Value

• Nonzero if successful.

Usage

For instance, if you want to draw a shadow for an edit control, use the following code:

CRect rcEdit;
m_Edit.GetWindowRect(&rcEdit);
ScreenToClient(&rcEdit);
rcEdit.InflateRect( 2, 2, 0, 0 ); // shadow placement adjustment
        
CExtWndShadow _shadow;
_shadow.Paint(
    dcPaint, rcEdit,
    5, // shadow size
    CExtWndShadow::DEF_BRIGHTNESS_MIN, 
    CExtWndShadow::DEF_BRIGHTNESS_MAX,
    false
);

Sample

The ShadowsTest sample project shows how to apply the class to some controls.

Reporting bugs

Your questions, suggestions, and bug reports may be posted either to the forum below or to the forum at the Prof-UIS website.

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