References ▼
The PNGWEBTUNERDLGPARAMS structure provides information used to initialize the dialog box created by the L_DlgPNGWebTuner function. After the user closes the dialog box, this structure is updated with information about the user's selections.
typedef struct _PNGWEBTUNERDLGPARAMS{L_UINT uStructSize;pBITMAPHANDLE pBitmap;L_BOOL bZoomToFit;COLORREF crTransparent;L_INT nPalType ;L_BOOL bAddWindowsColors ;L_INT nDitherType ;L_INT nBitsPerPixel ;L_INT nNumOfColors ;L_INT nTransparencyTolerance ;L_BOOL bTransparent ;L_UINT32 uDlgFlags ;LTCOMMDLGHELPCB pfnHelpCallback;L_VOID *pHelpCallBackUserData ;} PNGWEBTUNERDLGPARAMS, * LPPNGWEBTUNERDLGPARAMS ;
Size of this structure, in bytes. Use the sizeof operator to calculate this value.
Pointer to the bitmap handle that references the bitmap used for preview or processing.
Flag that indicates the initial zoom level for previewing the image. Possible values are:
| Value | Meaning |
|---|---|
| TRUE | Set the initial zoom level to "Zoom to fit". |
| FALSE | Set the initial zoom level to "Normal (1:1)". |
The color that will be transparent in the PNG image. This color is in RGB.
Value that indicates the type of palette to use. Possible values are:
| Value | Meaning |
|---|---|
| CRF_FIXEDPALETTE | Use the fixed palette. |
| CRF_OPTIMIZEDPALETTE | Create an optimized palette. |
Flag that indicates whether to use the identity palette. Possible values are:
| Value | Meaning |
|---|---|
| TRUE | Use the identity palette. |
| FALSE | Do not use the identity palette. |
Flag that indicates the dithering type to use. Possible values are:
| Value | Meaning |
|---|---|
| CRF_NODITHERING | Use nearest color matching |
| CRF_FLOYDSTEINDITHERING | Use Floyd-Steinberg dithering |
| CRF_STUCKIDITHERING | Use Stucki dithering |
| CRF_BURKESDITHERING | Use Burkes dithering |
| CRF_SIERRADITHERING | Use Sierra dithering |
| CRF_STEVENSONARCEDITHERING | Use Stevenson Arce dithering |
| CRF_JARVISDITHERING | Use Jarvis dithering |
| CRF_ORDEREDDITHERING | Use ordered dithering, which is faster but less accurate than other dithering methods. |
| CRF_CLUSTEREDDITHERING | Use clustered dithering |
The bits per pixel for the tuned bitmap. Valid values are: 1, 4, 8, 24, and 32 bpp.
When nBitsPerPixel is 8 or less (the image is using indexed colors), this value represents the maximum number of colors that the PNG image can have. Possible values range from 2 to 256. Indexed PNG images can have from 2 colors to 256 colors. Using fewer colors results in smaller files, but also reduces the quality of the image.
A tolerance value that determines how close a pixel's RGB value should be to the specified transparent color to be considered transparent. A tolerance of 0 means only the transparent color specified in crTransparent will be considered transparent. Specifying larger numbers will make more of the image transparent. Valid values are from 0 to 255.
Flag that indicates whether the PNG image will have a transparent color. Possible values are:
| Value | Meaning |
|---|---|
| TRUE | The PNG image will have a transparent color. |
| FALSE | The PNG image will not have a transparent color. |
✎ NOTE
Not all browsers are capable of presenting transparency for PNG images (especially for 24bit images).
User interface flags for this dialog which determines the layout and action of the dialog. This dialog does not support the Auto-Process feature; however it makes up for that by allowing the user to export tuned images directly from the dialog. This is done by setting the DIALOG_PNGWEBTUNER_SHOW_EXPORT flag. Possible values are:
| Value | Meaning |
|---|---|
| DLG_PNGWEBTUNER_SHOW_CONTEXTHELP | [0x00000001] Dialog should contain a context sensitive help icon. |
| DLG_PNGWEBTUNER_SHOW_PREVIEW | [0x00000002] Show a preview of the image in the dialog. The pBitmap member of this structure should contain a valid bitmap. |
| DLG_PNGWEBTUNER_SHOW_TOOL_ZOOMLEVEL | [0x00000004] Show the "Zoom to fit" and "Zoom Normal" toolbar buttons. The DLG_PNGWEBTUNER_SHOW_PREVIEW flag must be set in order to show these buttons. |
| DLG_PNGWEBTUNER_SHOW_TOOL_COLORPICKER | [0x00000008] Show the color button in the toolbar. |
| DLG_PNGWEBTUNER_SHOW_INFORMATION | [0x00000010] Show the Information group of controls. |
| DLG_PNGWEBTUNER_SHOW_ADDWINDOWCOLOR | [0x00000020] Show the Add Window Colors check box. |
| DLG_PNGWEBTUNER_SHOW_TRANSPARENCY | [0x00000040] Show the Transparency group of controls. |
| DLG_PNGWEBTUNER_SHOW_EXPORT | [0x00000080] Show the Export button instead of the OK button. |
| DLG_PNGWEBTUNER_SHOW_APPLY | [0x00000100] Show the Apply button in the dialog. The dialog will not apply any effect unless the user presses the Apply button. |
Pointer to an optional help callback function. If you do not wish to provide help to this dialog, use NULL as the value of this parameter. To provide help to this dialog, use the function pointer as the value of this parameter. The callback function must adhere to the prototype described in LTCOMMDLGHELPCB.
Void pointer that you can use to pass one or more additional parameters that the callback function needs. To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *. The callback function, which receives the address in its own pHelpCallBackUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. If the additional parameters are not needed, you can pass NULL in this parameter.