Inserting Images Dynamically

What is this page about?

This page describes inserting images dynamically.

You can insert images to your reports dynamically using image tags. To declare a dynamically inserted image within your template, do the following steps:

Add a textbox to your template at the place where you want an image to be inserted.
Set common image attributes such as frame, size, and others for the textbox, making the textbox look like a blank inserted image.
Specify an image tag within the textbox using the following syntax.

<<image [image_expression]>>

The expression declared within an image tag is used by the engine to build an image to be inserted. The expression must return a value of one of the following types:

A byte array containing an image data
A Stream instance able to read an image data
An Image object
A string containing an image URI, path, or Base64-encoded image data

While building a report, the following procedure is applied to an image tag:

The expression declared within the tag is evaluated and its result is used to form an image.
The corresponding textbox is filled with this image.
The tag is removed from the textbox.

Note – If the expression declared within an image tag returns a stream object, then it is closed by the engine as soon as the corresponding image is built.

By default, the engine stretches an image filling a textbox to the size of the textbox without preserving the ratio of the image. However, you can change this behavior in the following ways:

To keep the size of the textbox and stretch the image within bounds of the textbox preserving the ratio of the image, use the keepRatio switch as follows.
```
<<image [image_expression] -keepRatio>>
```
To keep the width of the textbox and change its height according to the ratio of the image, use the fitHeight switch as follows.
```
<<image [image_expression] -fitHeight>>
```
To keep the height of the textbox and change its width according to the ratio of the image, use the fitWidth switch as follows.
```
<<image [image_expression] -fitWidth>>
```
To change the size of the textbox according to the size of the image, use the fitSize switch as follows.
```
<<image [image_expression] -fitSize>>
```
To change the size of the textbox according to the size of the image without increasing the size of the textbox, use the fitSizeLim switch as follows.
```
<<image [image_expression] -fitSizeLim>>
```

Note – If the size of the image is greater than the size of the textbox, then the fitSizeLim switch acts like fitHeight or fitWidth. Otherwise, the fitSizeLim switch acts like fitSize.

FAQ

Q: What data types can be returned by the image expression?
A: The expression may return a byte[] containing raw image bytes, a System.IO.Stream that can read the image data, a System.Drawing.Image object, or a string that holds an image URI, a file path, or a Base64‑encoded image.
Q: How does the engine treat a Stream returned from the image expression?
A: After the image is built, the engine automatically closes the Stream. You do not need to close it manually, and you should not use the stream after the tag is processed.
Q: Which switch should I use to keep the original aspect ratio of the image?
A: Use the -keepRatio switch. It stretches the image to fill the textbox while preserving its width‑to‑height ratio.
Q: How can I make the textbox automatically resize to match the image dimensions?
A: Apply the -fitSize switch. The engine will adjust the textbox size so that it exactly matches the size of the inserted image.
Q: What does the -fitSizeLim switch do, and when should I use it?
A: -fitSizeLim resizes the textbox to the image size but never makes the textbox larger than its original dimensions. If the image is larger, the switch behaves like -fitHeight or -fitWidth; otherwise, it behaves like -fitSize. Use it when you want to limit the textbox growth while still fitting the image proportionally.

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