CoderCards - Class Libary Version

This is a precompiled function version of the Azure Functions sample CoderCards.

About the sample

This sample uses the new precompiled function feature. The project also uses WebJobs attributes instead of function.json. Use the FunctionName attribute to provide the name that will appear in the portal.
There are two versions of the project:
- CoderCards.csproj, which requires Visual Studio 2017 Update 3 and the Azure Functions Tools VSIX. When the project is built, the file function.json is generated in the build output folder.
- CoderCardsWebProj.csproj, which is a regular web project. To convert attributes to function.json, it runs Runner.exe as a post-build step. To make the project runnable with F5, you must modify the project start action to launch the Azure Functions Core Tools. (See intructions below.)
There are two functions defined in this project:
- RequestImageProcessing. HTTP trigger that writes a queue message. The request payload must be in the following form:
```
    {
      "PersonName": "Scott Guthrie",
      "Title": "Red Polo Connoisseur",
      "BlobName": "Scott Guthrie-Red Polo Connoisseur.jpg"
    }
```
- GenerateCard. Queue trigger that binds to the blob specified in the BlobName property of the queue payload. Based on the predominant emotion of the input image, it generates a card using one of 4 card templates.
  - The card is written to the output blob container specified by the app setting output-container.

Key	Description
AzureWebJobsStorage	Storage account connection string
EmotionAPIKey	Key for Cognitive Services Emotion API
input-queue	Name of Storage queue for to trigger card generation. Use a value like "local-queue" locally and "input-queue" on Azure
input-container	Name of Storage container for input images. Use a value like "local-card-input" locally and "card-input" on Azure
output-container	Name of Storage container for output images. Use a value like "local-card-output" locally and "card-output" on Azure
HOME	Set to "." when running locally. Is automatically set on Azure
SITE_PATH	Use "." when running locally. Use `site\\wwwroot` on Azure

If you're using Visual Studio 2017 Update 3 and the Azure Functions Tools VSIX, open the project CoderCards.csproj. F5 will automatically launch the Azure Functions Core tools.
If you're using CoderCardsWebProj.csproj, you must customize the project start action to launch the Azure Functions Core tools. See screenshot below.
1. Install the Azure Functions Core Tools from npm.
2. Right-click CoderCardsWebProj and open Properties.
3. In the Web tab, choose Start External Program
4. For the program path, enter the path to func.exe for the Azure Functions CLI. The path will be similar to like C:\Users\USERNAME\AppData\Roaming\npm\node_modules\azure-functions-cli\bin\func.exe
5. For Command line arguments set host start --cors *
6. For Working directory, specify the root of the project CoderCardsWebProj on your machine.

TBD

Send an HTTP request using Postman or CURL, specifying the path of the blob you just uploaded:

{
  "PersonName": "My Name", 
  "Title": "My Title",
  "BlobName": "BlobFilename.jpg"
}

The demo uses System.Drawing, which is NOT recommended for production apps. To learn more, see Why you should not use System.Drawing from ASP.NET applications.
Happy faces get a multiplier of 4, angry gets a multiplier of 2. I encourage you to tweak for maximum comedic effect!

Creating an HTTP trigger that writes a queue message is just one line of code!
Using a queue message to trigger blob processing is preferable to a blob trigger, as it is easier to ensure transactional processing. Also, blob triggers can be delayed for up to 10 minutes on the Consumption plan.
By binding to a POCO, you can use the payload of a trigger to configure an input binding. In this example, we binding to the BlobName property in the queue message.
The input binding is just a byte array, which makes it easy to manipulate with memory streams (no need to create new ones). Other binding types for C# are Stream, CloudBlockBlob, etc, which is very flexible. The output binding is just a stream that you just write to.