Text overlay – Medialooks Help Center

You can add text overlays to a video frame by using a single method - MFPrint.

This method includes the following parameters:

_bsText – the text you would like to overlay.
_dblTextSize – font size measured in relative units, where size 1.0 is 1/24 of screen height.
_pRect – the rectangle area (MF_RECT) where the text overlay will appear.
_eMFTextFlags – a set of additional flags (eMFTextFlags) to align the text.
_bsExtraParam – a string with additional parameters for text formatting (described below)

Parameter _bsText can be just plain text or it can contain the following XML tags:

text (font) – style defined by parameters: face (e.g., "Times New Roman", "Arial", "Tahoma", etc.), size (in ems) and color.
img – embedded image with required parameter src = <path to image> and optional parameters width, height and size = <height relative to text line> (e.g., if size = 2.0 image height will be equal to double text line height).
b – bold.
i – italics.
u – underline.
s – strike out.

Additional parameters are introduced as a string in order to achieve greater flexibility: adding new formatting options will not change the code for calling the method.

In order to add formatting, we can change the _bsExtraParam. Here are the available parameters:

face – font name, such as 'Times New Roman', 'Arial', etc.
weight – font weight with possible numeric values from 0.0 to 2.0.
italic – italic type. Possible values are true and false.
bold – boldface type. Possible values are true and false.
oblique – bold italic type. Possible values are true and false.
stretch – font-stretch with possible numeric values from 0.0 to 2.0.
word-wrap – automatically moving the word to the next line if a line of text is filled. Possible values are true and false.
line-spacing – line height, or distance between one baseline to another. Possible values are from 0.0 to 10.0. By default, the line height is 1.15.
baseline – the distance from the top of the line to baseline. By default, the baseline is 0.8.
align – horizontal alignment of text. Possible values are: left, center, right and justify.
vert-align – vertical alignment of text. Possible values are top, center, and bottom.
color – font color. HEX-code value ('0x00f0ff') or color list ('red', 'green', 'blue', etc.). Can be defined with a transparency level in brackets: 'red(50)', '0xffffff(80)'.
outline – width of text outline measured in relative units, where outline=1.0 is an outline with the width of 1/240 of screen height.
outline-color – color of text outline. HEX code value, for example, '0xff0000' or color list (red, green, blue, etc.). Can be defined with a transparency level in brackets: 'red(50)', '0xffffff(80)'.
bg-color – background color. HEX code value, for example, '0xff0000' or color list (red, green, blue, etc.). Can be defined with a transparency level in brackets: 'red(50)', '0xffffff(80)'.

A sample text overlay looks like:

// grab frame from source
MFFrame sourceFrame;
mySource.SourceFrameGet(-1, out sourceFrame, "");
// configure parameters for overlay
string textToOverlay = "My Sample Text";
double textSize = 3.0;
MF_RECT textRectangle= new MF_RECT();
textRectangle.dblHeight = 300;
textRectangle.dblPosX = 100;
textRectangle.dblPosY = 150;
textRectangle.dblWidth = 600;
textRectangle.eRectType = eMFRectType.eMFRT_Absolute;
eMFTextFlags textFlags = eMFTextFlags.eMFT_WordBreaks;
string formattingParameters = "face='Times New Roman' weight='1.5' italic='true' bold='true' align='justify' vert-align='center' color='red'";
// overlay text
sourceFrame.MFPrint(textToOverlay, textSize, ref textRectangle, textFlags, formattingParameters);
// put frame to receiver
myReceiver.ReceiverFramePut(sourceFrame, -1, "");

Here is example of this code from Draw Frames Sample:

<text color=red>M</text>Formats <text size=0.9 face='Courier New'>IMFFrame::MFPrint</text> support:
<tab>- Different <text color=yellow>colors</text>
<tab>- Different <text size=1.0 face='Courier New'>fonts</text>
<tab>- Different styles: bold italic underline <s>strikeout</s>
<tab>- Different <text size=2.0>text</text> <text size=0.5>size</text>
<tab>- Add even pictures: <img size=3.0 src="C:\Users\Vsevolod\Pictures\logo.png"</img>

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