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# Delegate PDFViewThumbAsyncDelegate

A delegate that will be called after GetThumbAsync retrieves a thumbnail from the on-disk thumbnail cache.

###### Namespace: pdftron.PDF

###### Assembly: PDFNet.dll

##### Syntax

    public delegate void PDFViewThumbAsyncDelegate(int page_num, bool was_thumb_found, Bitmap thumb_buf, int thumb_width, int thumb_height, object custom_data)

##### Parameters

Type | Name | Description
--- | --- | ---
int | page_num | The page number of the thumbnail.
bool | was_thumb_found | A boolean value which is true if the thumbnail could be retrieved from the persistent cache, and false otherwise.
Bitmap | thumb_buf | A pointer to the thumbnail image. This buffer's size, in bytes, is equal to thumb_width * thumb_height * 4.
int | thumb_width | The width, in pixels, of the thumbnail image.
int | thumb_height | The height, in pixels, of the thumbnail image.
object | custom_data | Custom data passed into GetThumbAsync.

### Constructors

#### PDFViewThumbAsyncDelegate(object, IntPtr)

##### Declaration

    public PDFViewThumbAsyncDelegate(object A_0, IntPtr A_1)

##### Parameters

Type | Name | Description
--- | --- | ---
object | A_0 |
IntPtr | A_1 |

### Methods

#### BeginInvoke(int, bool, Bitmap, int, int, object, AsyncCallback, object)

##### Declaration

    public IAsyncResult BeginInvoke(int page_num, bool was_thumb_found, Bitmap thumb_buf, int thumb_width, int thumb_height, object custom_data, AsyncCallback callback, object obj)

##### Parameters

Type | Name | Description
--- | --- | ---
int | page_num |
bool | was_thumb_found |
Bitmap | thumb_buf |
int | thumb_width |
int | thumb_height |
object | custom_data |
AsyncCallback | callback |
object | obj |

##### Returns

Type | Description
--- | ---
IAsyncResult |

#### EndInvoke(IAsyncResult)

##### Declaration

    public void EndInvoke(IAsyncResult result)

##### Parameters

Type | Name | Description
--- | --- | ---
IAsyncResult | result |

#### Invoke(int, bool, Bitmap, int, int, object)

##### Declaration

    public void Invoke(int page_num, bool was_thumb_found, Bitmap thumb_buf, int thumb_width, int thumb_height, object custom_data)

##### Parameters

Type | Name | Description
--- | --- | ---
int | page_num |
bool | was_thumb_found |
Bitmap | thumb_buf |
int | thumb_width |
int | thumb_height |
object | custom_data |