I have a signature pad designed in my XAML with the help of custom renderers. I am getting the user's signature and saving the signature as an image successfully. However, even when the user has not signed on the signature, and when I am clicking the Save button, an image is saved as an empty image. Is that any boolean property to know without image touch to set false?
Following renderer am using
https://github.com/15mgm15/Xamarin-Forms-Signature
You can also judge if the user has completed the signature before saving it. Here's the code snippet below for your reference:
Xaml:
<controls:SignaturePadView
x:Name="signatureView"
StrokeWidth="3"
StrokeColor="BlackWhite"
BackgroundColor="Black" />
Code in backend:
if (!signatureView.IsBlank)
{
// Save signature image
}
else
{
//display the alert to finish the sign
}
Related
I have implemented a custom DataTemplateSelector according to: GitHub Xamarin Forms.
This allows for a datatemplate to be selected based on an item, which is received through a data binding. This works fine to select a proper datatemplate and render it. However, I am now at a point where I want to add custom controls to this datatemplate (custom buttons). This works on any other page, but for some reason not in this datatemplate.
The relevant lines in the datatemplate:
xmlns:controls="clr-namespace:Universal_ONE.Views.Controls"
<controls:IconButton Command="{Binding RobotLocationSave}"
Image="{StaticResource BoltBlack}"/>
The part the datatemplate is selected and created:
var templateToUse = templateSelector.SelectTemplate(item, null);
View view = (View)templateToUse.CreateContent();
view.BindingContext = bindingContext;
In the catch block I get the error (after calling CreateContent()):
Xamarin.Forms.Xaml.XamlParseException: Position 371:26. Type controls:IconButton not found in xmlns clr-namespace:Universal_ONE.Views.Controls
The problem has to be with the CreateContent(), since using the control outside of this datatemplate works.
EDIT 1
I've created a Minimal Working Example: GitHub.
The datatemplate is now hardcoded, so I'm sure that one is selected.
The same parseexception gets thrown.
I am trying to compile Xamarin.Forms myself so I can debug the framework itself. However, compiling is not going smooth; thus might take a bit longer.
EDIT 2
A bit more info on the MWE:
The MainPage.xaml has the default Xamarin.Forms app code. Below I've added a custom control, which is simply a frame with a label. The text of this label is set via a bindableproperty (not really relevant). Below this control is the datatemplatecontrol added, which in turn calls the datatemplateselector, which returns the datatemplate. This datatemplate contains the same control as the mainpage. Thus the rendered app should have 2 controls. However, in de datatemplatecontrol you can breakpoint on the catch statement (look for my comment). This is where the parseexception will show, which is caused after calling CreateContent() on the datatemplate.
EDIT 3
I've not been clear enough I think. But you have to put a breakpoint on line 41 of datatemplatecontroler.cs. Since the content of the datatemplate is set to null if the createcontent() fails, thus fails gracefully. When hitting the breakpoint you can read the parseexception.
EDIT 4
I've made an issue and a pull request on the Xamarin repository: GitHub. The problem resides with the XamlParser, which has a small bug where it selects the wrong assembly. Inside the issue I've mentioned a workaround which can be used for now.
I try to download your example and run it. When I run to Content = CreateTemplateForItem(ItemTemplate); the program does not report an error, so the program skips the catch method. Here is a screenshot of the runtime:
Then I tried to actively throw an exception in the try statement (throw new Exception();) to make the program enter the catch method, Here is a screenshot of the runtime:
I'd like to attach images to certain cells of my Google spreadsheet, to appear upon hovering the mouse upon that cell, similar to how the native text-only regular cell notes (Shift+F2) appear.
Natively, Google Sheets supports inserting images in the cell. My image sizes are however too big, and I'd have to make the row/column width/height huge for them to be displayed at 100%. Plus, I'd want the images to only appear upon mouseover, and not always be visible.
(I should add that the functionality I describe is actually very easily achievable in Excel, which allows setting a picture-background for cell comments, something that Google Sheets does not.)
I discovered a Google Sheets addon which seems to extend regular cell notes to include richer content, including images. Inconveniently, it requires each image be uploaded to an image server rather than be loaded from the PC. That would have still been fine, except I couldn't get it to achieve the above stated goal.
Finally, I found this suggested workaround, which for me does not work, in the sense that the image is not loaded as a preview upon mousing over the URL (whether it ends with .jpg or not), only the URL itself is:
Interestingly, the effect I'm after actually exists in Google Docs, when the link isn't even an image but just a page:
Issue:
There is no native way to trigger actions on hover events in Sheets, and there is no way to retrieve images that have been uploaded from the computer and don't have a valid URL. This greatly limits what you can accomplish.
Nevertheless, there are workarounds available that can get you close to the functionality you're asking for.
Workaround (showModelessDialog):
You could, for example create a modeless dialog whose purpose would be to show the image corresponding to the selected cell.
Ideally, onSelectionChange trigger would be used, since this trigger to refresh the modeless dialog with current image when the user changes the selected cell, but since creating a modeless dialog requires authorization, simple triggers cannot run services that require authorization, and onSelectionChange is only available as a simple trigger (cannot be installed), that won't be possible.
So one possible workflow could be the following:
Show a modeless dialog when the spreadsheet is opened by a user.
The user selects the cell with the image that should be shown.
User clicks a button in the modeless dialog (or the previous image) to refresh the modeless dialog with the currently selected image.
How to do this:
To achieve this, you can follow these steps:
Install onOpen trigger that creates modeless dialog when the user opens the spreadsheet (the trigger needs to be installed, since, as I mentioned, simple triggers cannot use services that require authorization). To do that, go to the Apps Script editor (selecting Tools > Script editor), copy this function to your Code.gs file, and install the trigger following these steps:
function onOpenTrigger(e) {
var html = HtmlService.createTemplateFromFile("Page").evaluate()
.setWidth(800) // Change dimensions according to your preferences
//.setHeight(600) // Change dimensions according to your preferences
SpreadsheetApp.getUi()
.showModelessDialog(html, "My image");
}
Create the HTML template corresponding to the modeless dialog. The idea here would be: when the page loads, the currently selected image is shown. If the button (or the image itself) gets clicked, the page will refresh with current image (see retrieveImage and refreshImage). Create an HTML file in the editor via File > New > HTML file, and copy the following code:
<!DOCTYPE html>
<html>
<head>
<base target="_top">
</head>
<body onload="retrieveImage()">
<img id="currentImage" onclick="retrieveImage()" alt="No image is selected" width="600">
<button onclick="retrieveImage()">Click to refresh image!</button>
</body>
<script>
function retrieveImage() {
google.script.run.withSuccessHandler(refreshImage).getSelectedImage();
}
function refreshImage(imageUrl) {
if (imageUrl) document.getElementById("currentImage").src = imageUrl;
}
</script>
</html>
Back in your script file (.gs), create a function to retrieve the image URL from current cell (in case this cell has an image). This function will get called by the modeless dialog when it loads and when its button is clicked. It could be like this (regex is used to retrieve that — see this answer:
function getSelectedImage() {
var formula = SpreadsheetApp.getActiveRange().getFormula();
var regex = /=image\("(.*)"/i;
var matches = formula.match(regex);
return matches ? matches[1] : null;
}
Note:
You can adapt the dimensions of both the selected image (<img width="" height="">) and the modeless dialog (.setWidth, .setHeight) according to your preferences.
Reference:
Dialogs and Sidebars in G Suite Documents
Installable Triggers: Managing triggers manually
getActiveRange()
I need to display an image using a URL that I receive from Push Notification. I tried many docs and blogs but couldn't find the correct solution. I don't want to download and store in DB.
the easiest way that i found to do this...
map the url to an image box and make it visible, set an events event to success, set action to Set property, set component name to what you want to show the image, set property to visibile and value to true leave check box empty as in this image success to html function
I have an uploader that has two modes where it uploads different file types. Which one is active depends on what the user is doing. I am using FineUploaderBasic.
Right now to dynamically modify the allowedExtensions I do something like this:
if(type==<?=Campaign_Placement::AD_TYPE_USER_FLASH?>) // SWF
uploader._options.validation.allowedExtensions = ['swf'];
else // Static image
uploader._options.validation.allowedExtensions = ['jpeg', 'jpg', 'gif', 'png'];
uploader.reset(); // Resets with the new extensions
And to modify the acceptFiles:
if(type==<?=Campaign_Placement::AD_TYPE_USER_FLASH?>) // SWF
$('input[name="userfile"]').attr("accept", "application/x-shockwave-flash");
else // Static image
$('input[name="userfile"]').attr("accept", "image/jpeg, image/jpg, image/gif, image/png");
Both are ugly ways to do this, would appreciate a simple way to do both of these through the API, or some other elegant solution. Thanks!
You have 3 other options to solve this problem:
Don't set the allowedExtensions validation value at all. Then contribute a validate event handler that returns false if the user has submitted an invalid file, based on the value of the select you have provided.
Simply construct or re-construct the uploader instance whenever the user changes their selection.
Consider using the relatively new extraButtons feature, where you can connect additional upload buttons to a single Fine Uploader with varying validation options. For example, you can contribute some default allowed extensions (tied to the default upload button), and then provide an extraButtons button with alternate allowedExtensions. Simply display the appropriate button via JavaScript when the user changes their selection.
I need to upload the photo of a user with his details from asp.net mvc3 razor view. The image selected by the user has to be shown as thumbnail before submitting the form.
The model of the view contains a byte array property called Photo. On page load i am converting this byte array to base 64 string and showing it in . this is working properly .
Now i need to show the thumbnail of the image selected by the user. And when he clicks on submit button i need to bind the selected image to the model property Photo.
After googling , i came to know that showing thumbnail is not possible until I upload that image. I tried Uploadify but its UI behavior is not what i am expecting. I also tried the article http://www.dustinhorne.com/post/2011/11/16/AJAX-File-Uploads-with-jQuery-and-MVC-3.aspx, but it is also not suitable in our scenario.
can anyone help me by sharing their experience achieving this scenario.
Thanks in advance.
You could achieve this using HTML5 File API. Take a look at the following article and more specifically the Showing thumbnails of user-selected images section which illustrates an example of how you could achieve that without uploading the image to the server.
And if you want to support legacy browsers that do not yet support the HTML5 File API you could use the jQuery.form plugin which allows you to easily send the contents of a given form to the server using AJAX and it also supports file uploads. So basically you could subscribe to the .change() event of the file input or the .click() event of some see thumbnail ... button and then submit the form to a controller action using AJAX:
$('#myform').ajaxSubmit({
url: '#Url.Action("thumbnail")',
success: function(result) {
// the result variable will contain the result of
// the execution of the Thumbnail action.
// could be a BASE64 encoded representation of
// the thumbnail you generated on the server and then
// simply set it to the src property of your preview `<img>`
// element using the Data Uri scheme
}
});