I made PNGs for custom markers on my GoogleMap view. By using e.g.:
BitmapDescriptor bikeBlack = await BitmapDescriptor.fromAsset(const ImageConfiguration(), "assets/images/bike_black.png")
I obtain an object that I can use as a marker directly. However, I need to be able to change the brighness as well for about 50 markers of 4 different types, during runtime. The only possible solution I have come up with so far is creating 1024 different PNGs. This will increase app size by about 2MB but it might be a lot of work to do..
I cannot really afford using await statements since they slow the app down considerably. But if I have to, I can force myself to live with that.
As far as I can tell, a marker icon has to be a BitmapDescriptor. But I cannot find a way to change the brightness of such a BitmapDescriptor.
I'm close to just giving up and just writing a python script that will generate the 1,024 PNGs for me. But there must be a nicer and more efficient solution. If you have one, please let me know.
[EDIT]:
I went with creating 1024 images. For anybody in the same situation, this is the script I used:
from PIL import Image, ImageEnhance
img = Image.open("../img.png")
enhancer = ImageEnhance.Brightness(img)
for i in range(256):
img_output = enhancer.enhance(i / 255)
img_output.save("img_{}.png".format(i), format="png")
Related
I'm trying to find out the dimensions (width and height) of an asset file but without loading it into memory, or with as little memory usage as possible.
I'm currently doing:
Image _mainMenuTable = Image.asset("images/main_menu_table.png");
but won't that make a widget into memory and also load the image onto it ? Even if I don't display it anywhere.
I've also tried creating an AssetImage, which I'm already doing to set as the background image of a Container, but I can't retrieve the dimensions of the image from it.
Any ideas if there's a better way that Image.asset? This way, I am indeed getting my width and height dynamically, but it loads it into memory twice, no? Once as an Image and once as an AssetImage
Disclaimer: it's my second week into Flutter, so please be gentle in case the answer is obvious.
Cheers!
You just need to use the File class from the dart:io package.
Example -
import 'dart:io';
void main(){
var file = File('file_path');
file.length().then((len) => print(len)); //prints bytes
}
I'm trying to grab a screenshot with renderer.domElement.toDataURL("image/png"), and save it to a file.
The image is the right size, but it's black.
I have preserveDrawingBuffer turned on.
I think I'm decoding and saving the file correctly, because when I hexdump it I can see the correct initial characters for the PNG format, as well as the IHDR and IDAT chunk headers. However the closing IEND is missing.
Any known issues here? Hints? Windows 7/Firefox up to date if it matters.
Thanks... (Sorry if this is dumb, I'm very new to three.js)
I had somewhat similar problems with Windows 7/Firefox. PNG Data URL's would be randomly truncated or something, much shorter than a successful PNG export. Trying to set that data url as image src resulted in "Image corrupt" exception or something in FF. As little sense it makse, setting a small window.setTimeout (10ms) between rendering and getting the data URL helped in my case. Maybe Firefox needs a rest from the JS engine before it refreshes some canvas internal state or something.. weird.
I switched to JPG format (smaller files => truncation less of an issue?) and still saw it not working, then I tried this tip which I found here
If you want to save data that is derived from a Javascript
canvas.toDataURL() function, you have to convert blanks into plusses.
If you do not do that, the decoded data is corrupted:
<?php
$encodedData = str_replace(' ','+',$encodedData);
$decodedData = base64_decode($encodedData);
?>
This worked. Thanks, Mekal.
This tip seems to apply to JPGs only. I saw PNGs decoding correctly without the + replacement, and corruptly with it. I can use JPGs so my personal problem is solved. However I never saw a PNG that wasn't black even when decoded correctly and not truncated.
Kind of a lousy situation either way, I feel like. What is up with the +'s?
A black texture is a sign that you did not indicate the texture needs to be updated.
Also, you do not need to use canvas.toDataURL(). You can pass in the canvas reference to the THREE.Texture object.
var canvas = document.getElementById('#myCanvas');
var texture = new THREE.Texture(canvas);
texture.needsUpdate = true;
// Now render the scene
I'm building an App with actionscript 3.0 in my Flash builder. This is a followup question this question.
I need to upload the bytearray to my server, but the function i use to convert the bitmapdata to a ByteArray is super slow, so slow it freezes up my mobile device. My code is as follows:
var jpgenc:JPEGEncoder = new JPEGEncoder(50);
trace('encode');
//encode the bitmapdata object and keep the encoded ByteArray
var imgByteArray:ByteArray = jpgenc.encode(bitmap);
temp2 = File.applicationStorageDirectory.resolvePath("snapshot.jpg");
var fs:FileStream = new FileStream();
trace('fs');
try{
//open file in write mode
fs.open(temp2,FileMode.WRITE);
//write bytes from the byte array
fs.writeBytes(imgByteArray);
//close the file
fs.close();
}catch(e:Error){
Is there a different way to convert it to a byteArray? Is there a better way?
Try to use blooddy library: http://www.blooddy.by . But i didn't test it on mobile devices. Comment if you will have success.
Use BitmapData.encode(), it's faster by orders of magnitude on mobile http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/BitmapData.html#encode%28%29
You should try to find a JPEG encoder that is capable of encoding asynchronously. That way the app can still be used while the image is being compressed. I haven't tried any of the libraries, but this one looks promising:
http://segfaultlabs.com/devlogs/alchemy-asynchronous-jpeg-encoding-2
It uses Alchemy, which should make it faster than the JPEGEncoder from as3corelib (which I guess is the one you're using at the moment.)
A native JPEG encoder is ideal, asynchronous would be good, but possibly still slow (just not blocking). Another option:
var pixels:ByteArray = bitmapData.getPixels(bitmapData.rect);
pixels.compress();
I'm not sure of native performance, and performance definitely depends on what kind of images you have.
The answer from Ilya was what did it for me. I downloaded the library and there is an example of how to use it inside. I have been working on getting the CameraUI in flashbuilder to take a picture, encode / compress it, then send it over via a web service to my server (the data was sent as a compressed byte array). I did this:
by.blooddy.crypto.image.JPEGEncoder.encode( bmp, 30 );
Where bmp is my bitmap data. The encode took under 3 seconds and was easily able to fit into my flow of control synchronously. I tried async methods but they ultimately took a really long time and were difficult to track for things like when a user moved from cell service to wifi or from tower to tower while an upload was going on.
Comment here if you need more details.
Up until now, this block of code has been using to build documents with text for several months with no snags. I am now trying to dynamically add images. I've spent about two days staring at code and researching and am at an end. I suspect the issue is that relationships are not being created (more details below.) Maybe not?
//set stuff up...
WordprocessingDocument doc = WordprocessingDocument.Open(fsPat, true, new OpenSettings(){
AutoSave = true,
MarkupCompatibilityProcessSettings = new MarkupCompatibilityProcessSettings(MarkupCompatibilityProcessMode.ProcessAllParts,
DocumentFormat.OpenXml.FileFormatVersions.Office2007),
MaxCharactersInPart = long.MaxValue
});
MainDocumentPart mainPart = doc.MainDocumentPart;
.
.Other stuff goes here
.
//now the fun...
Run r2 = new Run();
// Add an ImagePart.
ImagePart ip = mainPart.AddImagePart(ImagePartType.Png);
string imageRelationshipID = mainPart.CreateRelationshipToPart(ip); //
using (Stream imgStream = ip.GetStream())
{
System.Drawing.Bitmap b = new System.Drawing.Bitmap("myfile.png");
b.Save(imgStream, System.Drawing.Imaging.ImageFormat.Png);
}
Drawing drawing = BuildImage(imageRelationshipID, "name"+imageRelationshipID.ToString(), 17, 17);
r2.Append(drawing);
p.Append(r2);
The image part is essentially copied from http://blog.stuartwhiteford.com/?p=33) and is running in a loop presently. I also copied his BuildImage() function and use it as-is.
When I open the resulting docx, I see red Xs where the images are saying "This image cannot currently be displayed."
When I open the zip, the images will appear in root/media, but not root/word/media as I'd expect. I also cannot find the images referenced in any of the relationship files. Ideally they'd be in root/word/_rels/document.xml.rels. You'll notice I changed how imageRelationshipID is set hoping to fix this. It didn't.
Please help. Thank you.
So... It seems like OpenXML just hates me. I copied AddImagePart code from like 3-4 places among trying other things--none of which lasted long--and just could not get relationships to form. The implication I see is that they happen automatically with the AddImagePart function.
I ended up doing a complete workaround where I add all the pictures I might want to put and remove the Drawing nodes' parents of the ones I didn't want (Run nodes, generally.) Since these are very small pictures, it's feasible and in ways more elegant than trying to add them as necessary since I don't have to keep track of where images are stored on disk.
I've built a simple application that applies grid-lines to an image or just simple colors for use as desktop wallpaper. The idea is that the desktop icons can be arranged within the grid. The problem is that depending on more things than I understand the actual spacing in pixels seems to be different from system to system. I've learned that at least these things play a factor:
Resolution (duh)
Taskbar size and placement
Fonts
There has to be more than this. Maybe there's some api call that I don't know about?
there are a 1001 ways to get/set this (but I only know 2) :-D
Windows Register:
HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics
values are IconSpacing and IconVerticalSpacing
by code:
using System.Management;
public string GetWinIconSpace()
{
ManagementObjectSearcher searcher = new ManagementObjectSearcher("root\\CIMV2","SELECT * FROM Win32_Desktop");
foreach (ManagementObject wmi in searcher.Get())
{
try
{
return "Desktop Icon Spacing: " + wmi.GetPropertyValue("IconSpacing").ToString();
}
catch { }
}
return "Desktop Icon Spacing: Unknown";
}
and the 3rd that I never tried you can find it here
They might also be a size problem due to scaling algorithm if the requested size of the icon is not available.
(since an icon file is actually a collection of icons, as explained in this thread about Icons and cursors know where they came from, from the The Old New Thing)